Molecular alloys and restoring thermal energy by phase change

ABSTRACT

Compositions made up of one or more molecular alloys which are suitable for storing or restorng thermal energy at a temperature level T and over a time interval δ matching those required for a pareicular applicaion as a phase-change material, said alloys belonging to a phase diagram having a transition region wih a temperaure range which includes the required temperatre and has a near-horizontal geometric locus (EGC). Said compositions are useful as a phase-change materials, particularly in the agrifoodstuffs and paramedical industries.

This is a continuation of application No. 07/988,949, filed May 4, 1993now U.S. Pat. No. 5,997,762.

The invention relates to compositions useful as phase-change materialsfor storing and restoring thermal energy by latent heat.

Thermal energy may be stored in two main forms, namely sensible heat andlatent heat.

Storage of sensible heat in a material results in an increase in itstemperature or in the case of restoration in a reduction of itstemperature.

In contrast with storage by sensible heat, storage by latent heat isperformed isothermally if the material is pure, or with some variationin temperature in the case of mixtures: the main factor being the phasechange of the material.

Phase change materials (PCMs) are thus compounds capable of storing andrestoring thermal energy by means of their phase transitions, mostfrequently solid-to-liquid transitions, but also solid to solidtransitions.

When heated the material takes calories from the external medium andreaches a temperature T_(tr) (transition temperature), passing fromphase 1 to phase 2 by heat absorption. When the transition is completed,its temperature can rise again.

If the material is cooled, the converse transition takes place: atT_(tr) the material passes from phase 2 to phase 1 and restores to theexternal medium the energy which it had previously stored, whileremaining at the temperature T_(tr). The energy involved is thevariation in phase change enthalpy H.

Widely used PCMs are formed by ice and saline hydrates. Certaineutectics have also been proposed. However, these materials have thedisadvantage of operating at a single, non-adjustable temperature. Anumber of them, more particularly the saline hydrates, are corrosive andmelt irregularly, frequently causing segregations which are difficult tocontrol and which make the materials behave poorly in thermal cycling.

It has also been proposed to use organic compounds such as fatty acids,paraffin waxes or certain paraffin wax mixtures for the storage ofenergy.

Thus, French Patent 2 368 529 discloses the use of paraffin wax mixtureswhich are solid at 25° C. as PCMs. However, the aim of that patent is toimprove the thermal properties of such mixtures by the addition ofmetals, their oxides or their silicates. The example given relates toimproving the thermal properties of an 82/18 mixture ofn-docosane/n-tetracosane by the addition of magnesium oxides, alumina,emery, kaolin and aluminium in the proportion of 25 to 55% by weight.

However, this patent does not consider the advantage of the mixture ofparaffin waxes as such, or the conditions to be combined to enable it tomeet the demands of a given application at a defined temperature.

Applications W087/03290, EP 0 344 013 and EP 0 344 014 disclosepolyolefine composites containing phase change materials formed moreparticularly by mixtures of paraffin waxes of C₁₄ or above. Thesecomposites are intended for the storage of solar energy.

The paper given by Salyer at the 15th North American Thermal AnalysisSociety Conference, Cincinnati, Ohio, Sep. 21-24 1986, relates to theanalysis of crystalline paraffinic hydrocarbons more particularlyintended for the storage of solar energy. Mixtures of commerciallyavailable paraffin waxes are studied as regards their properties asphase change materials for this application.

That study relates to mixtures of alkanes in given proportions andformed by odd chains--i.e., chains with an odd number of carbon atoms(referred to hereinafter as Cni) (mixtures C15/C19, C17/C19); evenchains--i.e., with an even number of carbon atoms (referred tohereinafter as Cnp) (mixtures C14/C16, C16/C18, C16/C20); even and oddchains (C16/C17, C18/C19) or by Cni or Cnp of longer chains (>C20).Ternary mixtures are also reported (C16/C17/C18 , C17/C18/C19 ;C16/C18/C20 ; C17/C19/C21 ; C14/C17/C20 and C16/C19/C21), all used inthe concentration 0.25/0.50/0.25.

Similarly, Salyer reports on the results obtained with synthesisedmulti-component mixtures corresponding to commercially availableproducts.

However, the conditions used for the measurements do not allow a properassessment of the characteristics of the mixtures studied, nor thereforeto determine for what temperature they are really appropriate; neitherare the means stated for obtaining compositions for a particulartemperature, for example, one required precisely in a given application.

The work carried out by the Inventors in this field has shown that tomake highly reliable compositions which are actually suitable, thestarting compounds must meet precise demands evaluated by strictmethods.

This work led to the working out of novel compositions and novel phasechange materials.

It is therefore an object of the invention to provide novel compositionsworked out with reference to predetermined parameters which by theirphase change enable high quantities of energy to be stored and restoredby latent heat.

The invention also relates to the preparation of said phase changecompositions.

It also relates to the use of compositions of this kind as materialshaving a phase change over a narrow temperature range lying in atemperature band enabling industrial needs to be widely satisfied.

The compositions according to the invention, suitable more particularlyfor storing and restoring thermal energy by latent heat, arecharacterized in that they are formed by one or more molecular alloys,being

characterized as such by X-rays,

capable of storing or restoring thermal energy at a temperature T over atemperature range δ as required for a particular application as aphase-change material,

belonging to a phase diagram having, if the alloy is binary, a loop inthe case of total miscibility, or a partial loop in the case of partialmiscibility, or, if the alloy is ternary or above, a transition zone,said loop or zone lying in a temperature band including that which isrequired for a given application and whose geometric locus EGC (Equal GCurve) is slightly curved and close to horizontal, to ensure a δ notexceeding the required width,

having a behaviour satisfactory for thermal cycling,

said alloys being obtained from organic compounds

having the latent heat conventionally required to be phase-changematerials,

having a degree of molecular homeomorphism ε_(k) higher than 0.8 and,preferably, higher than 0.9 for the binary alloys, or having saidproperty for the various constituents taken in pairs if they aremulti-component alloys,

whose inter-molecular interactions are relatively comparable for thestructures of the various constituents.

The term "molecular alloy" means a single phase generated from theorganic compounds used for its production, said phase behaving like apure body from the aspect of crystallography. This single phase,obtained by syncrystallization can also be referred to by the terms:solid solution or mixed crystal.

The X-ray analyses were carried out by powder defractometry, moreparticularly in a Guinier Lenne or Guinier Simon chamber.

The term EGC (Equal G Curve) means the geometrical locus of the pointswhere solid and liquid (or solid 1 and solid 2) are in equilibrium atthe transition (for a binary), or in a general way the various phases inequilibrium at the transition have the same Gibbs energy (Ref: H. A. J.OONK, PHASE THEORY, ELSEVIER 1981).

The expression "satisfactory behaviour in thermal icycling" as usedhereinbefore means that repeated cycles of storing/restoring, moreparticularly exceeding 30 cycles in the case of low-repetitionapplications and approximately 5000 cycles in the case of highlyrepetitive applications, cause neither chemical modification norsegregation which might cause the material to deteriorate.

The temperatures and associated enthalpies are measured by differentialcalorimetric analysis following calibration performed according to theinvention in strictly the same experimental conditions as those of theanalyses, which enables compositions to be provided which are completelycharacterized more particularly as regards their thermodynamicproperties and which will be fully adapted to the envisaged applicationat a given temperature level.

The degree of molecular homeomorphism ε_(k) of the organic compoundsused to form the alloy is obtained by so superposing the two moleculesin question that the volume of overlap r is a maximum, in which casetheir non-overlapping volume in that position, is a minimum.

The degree of homeomorphism is given by the formula: ##EQU1##

ε_(k) approaches 1 as the sizes and shapes of the molecules approachuniformity. The practical method of obtaining ε_(k) will be found in thereference Haget et al., J. Appl. Cryst (1990), 23, 492-496.

Thus, for practically all temperatures compositions are available whosethermal behaviour in melting and solidification are comparable with thatof pure compounds.

The molecular alloys according to the invention, which form phase-changematerials and which are also referred to hereinafter by the abbreviationPCMMAs, have a thermal efficiency window δ, defined at 95% of H.

In this regard it will be recalled that the transition, moreparticularly the melting, of an alloy is a continuum extending fromT_(solidus) to T_(liquidus). The total storage interval is equal to|T_(sol) -T_(liq) |. The temperature T_(95%) (lying between T_(sol) andT_(liq)) of the PCMMAs is such that 95% of the transition energy isstored between T₉₅ % and T_(liq).

The range δ=|T_(95%) -T_(liq) | is therefore an efficiency window of thePCMMA (at 95%).

The PCMMAs will hereinafter be characterized by T₆₇, T being taken to beequal to T_(liq).

The invention relates more particularly to the compositions definedhereinbefore in which δ does not exceed approximately +8° C., moreparticularly +6° C., in a temperature band between -100° C. and +300° C.

Compositions particularly preferred according to the invention have athermal efficiency window not exceeding approximately +4° C., asmeasured in the strict conditions set forth hereinbefore, andadvantageously not exceeding +20° C., and even +1° C.

In one embodiment of the invention the organic compounds used to formthe molecular alloys are not miscible in all proportions prior to thetransition, but the level of invariancy which therefore characterizesthe phase diagram is narrow, of the order of a few per cent inconcentration, and in general shifted towards one of the startingcompounds. The crystalline forms involved are not necessarilyisomorphic. There are two possible cases: the shapes are non-isomorphic,in which case there are two kinds of solid alloys each characterized ata given temperature by a G curve, or the shapes of the startingconstituents are isomorphic, but their degree of isomorphism is notsufficient to lead to complete miscibility; a single G curve issufficient to describe all the alloys (at a given temperature T), but ithas two points of inflection, only those alloys being stable andtherefore usable whose concentrations are outside the segment of doubletangence.

In either case the portion(s) of the phase diagram(s) in question is(are) the one(s) situated outside the level of invariancy.

In another embodiment of the invention the organic compounds used toform the molecular alloys are miscible in all proportions prior to thetransition.

Their crystalline shapes are therefore isomorphic and their degree ofcrystalline isomorphism ε_(m) is close to 1.

The degree of crystalline isomorphism ε_(m) is defined for two compounds(a notion which can be generalized if necessary by taking the compoundsin pairs in the case of multi-component alloys) by so superposing thecrystalline lattices of the two compounds in question that the volume ofoverlap r is a maximum; in that case their non-overlapping volume, _(m),in that position is a minimum, and ##EQU2##

(Ref. Haget et al, given hereinbefore).

The solid-liquid loop can have three appearances:

that of a simple cigar shaped domain: the alloys which can be producedfrom the organic compounds will have a melting range Intermediate thoseof the constituents of the alloy,

that of a loop with a minimum point; in this case an alloy can beproduced which melts at temperatures lower than those of the compounds;

that of a loop with a maximum Gibbs point, certain of the alloysobtained melting at a temperature higher than that of the startingcompounds.

In another embodiment the miscibility of the compounds used is low; thephase diagram is characterized by a wide level of invariancy of eutectictype; a mixture of alloys is obtained which is particularly advantageousdue to its thermal window (δ=0) for the eutectic concentration and whichoperates at the temperature of the eutectic invariant. The compoundshave small ε_(k) s; they are either non-isomorphic, or isomorphic withlow ε_(m) s.

According to another embodiment of the invention the compositions inquestion are also characterized in that they contain one or more of theafore-defined organic compounds by way of doping agents present in molarproportions of at least 5%, the main compound(s) being present in aproportion of approximately 90% or more. This doping advantageouslyenables T to be adjusted in relation to a given application.

The molecular alloys according to the invention correspond moreparticularly to formula (I):

    A.sub.x.sbsb.a Z.sub.phd x.sbsb.z                          (I)

wherein

A is an acyclic or cyclic, saturated or unsaturated, optionallysubstituted organic compound, excluding benzene and substitutedbenzenes,

Z denotes one or more organic compounds differing from A but selectedfrom the meanings given for A,

the organic compounds represented by A and Z meeting the afore-definedcriteria, and

x_(a) and x_(z) denote the molar proportions of A and Z respectively.

The term acyclic organic compound means the straight or branched chaincompounds having 2 to 120 carbon atoms and more for the polymers. Thesecompounds are preferably alkanes, alkenes or alkynes.

The cyclic organic compounds are formed by one or more rings having 5 to30 carbon atoms, more particularly aromatic rings, such as naphthalene,anthracene, benzene being excluded. As a variant they are formed by oneor more heterocyclic compounds. The heterocyclic compounds areadvantageously selected from the nitrogenated heterocyclic compounds,for example imidazoles, pyridine, pyrimidine, pyridazine, oxygenatedheterocyclic compounds such as the oxazoles, oxygenated and nitrogenatedheterocyclic compounds such as the oxadiazoles or else sulphuratedheterocyclic compounds such as thiazole. According to another embodimentthe cyclic organic compounds contain one or more carbon rings and one ormore heterocyclic compounds.

The organic compounds represented by A and Z optionally contain one ormore substituents selected from the halogens F, Cl, Br, I, the --OH or--OR₁ groups, the alkyl, the alkene and alkyne groups, these variousgroups preferably having 1 to 8 carbon atoms, more particularly 1 to 4carbon atoms, the --COOH, --COOR₁, --COR₁, --CH₂ OH, --CH(R₁)--OH,--C(R₁, R₂)OH, or their ethers, --CHO, ##STR1## --CONH₂, --NH₂,--NH(R₁), or --N(R₁,R₂), =S, --SH, --NO₂, R₁ and R₂, which are identicalor different, being an alkyl group having 1 to 8 carbon atoms,preferably 1 to 4 carbon atoms, functional groups, for example, amine,ketone, sulfhydryl, amide, possibly forming one or more moieties of thechain. The substituents of the acyclic organic compounds also containthe afore-listed rings and heterocyclic compounds.

In the acyclic organic compounds or their ethers, the above substituentsoccupy any position on the carbon chain, and/or are situated at one orboth ends of the chain.

In the cyclic organic compounds, these substituents occupy any positionon the ring.

In a family of molecular alloys according to the invention, A and Zbelong to the same class of compounds.

One group of this family is formed by hydrocarbon chains, moreparticularly alkanes, alkenes or alkynes, except for the mixturesexpressly disclosed in the prior art documents mentioned hereinbefore.

Particularly preferred molecular alloys are prepared from straight orbranched chain, optionally substituted, alkanes containing from 8 to 100carbon atoms, as indicated hereinbefore.

The molecular alloys prepared from normal alkanes, having the chemicalformula C_(n) H_(2n+2) (C_(n) for short) will be referred to hereinaferby the term ALCAL.

In this family all the intermolecular interactions are of Van Der Wallstype, giving very low G_(excess) both for solid solutions and for liquidsolutions, which induces only slightly curved EGC curves.

The ALCALs deemed to be acceptable--i.e., meeting the afore-definedcriteria--exhibit excellent behaviour in thermal cycling; they canwithstand several thousand cycles without damage (on condition thatsublimation is avoided, which might alter their composition). This isdue to the joint actions of the low δ, the fact that they are chemicallyinert, and the fact that their densities are similar. Moreover,supercooling phenomena are very slight or even non-existant, as long asconditions of utilization are maintained which are close to those of theapplication envisaged hereinafter.

They also have the advantage of being chemically inert, non-corrosiveand water-impermeable. They are also acceptable from healthconsiderations.

Acceptable ALCALs, covering a wide temperature band, for example, asmost generally required in industry, are formed by chains having from 8to 100, more particularly from 8 to 50 carbon atoms.

In these ALCALs, the constituent chains are Cnp or Cni or else Cnp andCni. The chains can be consecutive, of the type Cni/Cni, or Cnp/Cnp orCni/Cnp, or Cnp/Cni. As a variant, they differ by a number of moieties,more particularly by more than 4 or 5 carbon moieties. ALCALs may bementioned, for example, which contain at least one chain having 14carbon atoms or more, the or each other chain containing more than 5supplementary carbon moieties.

In one particular arrangement according to the invention, theaforementioned ALCALs contain at least one chain having one or moresubstituents, for example, those defined hereinbefore.

Among these substituents the carboxyl groups, esters and halogens may bementioned; they can advantageously occupy one or both of the ends of thechain.

In dependence on the requirements for a given application, a man skilledin the art will select the most appropriate substitutions to obtain therequired value T. Similarly, the proportions of each chain will readilybe selected by considering the diagrams of attributes δ, as illustratedby the Examples.

As indicated hereinbefore, one or more of the constituents of the ALCALcan be present by way of doping agent. The molar proportion of eachdoping agent is in that case of the order of less than 5%.

In another group, the alloys of the invention are prepared frommonocyclic or polycyclic, more particularly aromatic organic compounds,with the exception, as indicated hereinbefore, of substituted orunsubstituted benzene.

In one embodiment, heterocyclic compounds are used.

In yet another group the alloys are formed from hydrocarbon chainscontaining one or more rings and/or one or more heterocyclic compounds.

It will be recalled that in one advantageous embodiment of theinvention, the various alloys are doped.

In yet another group according to the invention, the organic compoundsare polymer chains.

In another family of alloys according to the invention, A and Z belongto different classes of compounds.

Preferred alloys of these different families are binary and correspondto the formula (II):

    A.sub.x.sbsb.a B.sub.x.sbsb.b                              (II)

where x_(a) +x_(b) =1, i.e., A_(1-x) B_(x)

Other alloys are ternary and have the formula (III):

    A.sub.x.sbsb.a B.sub.x.sbsb.b C.sub.x.sbsb.c               (III)

where x_(a) +x_(b) +x_(c) =1

Yet other alloys are quaternary and correspond to the formula (IV):

    A.sub.x.sbsb.a B.sub.x.sbsb.b C.sub.x.sbsb.c D.sub.x.sbsb.d(IV)

where x_(a) +x_(b) +x_(c) +x_(d) =1

In these formulae the various constituents A, B and, where applicable, Cand D and the indexes corresponding to the respective molarconcentrations correspond to the requirements defined hereinbefore andB, C and D have the meanings given hereinbefore for A, but differ fromone another.

Other alloys contain more than four organic compounds, namely 5, 6 ormore.

The invention also relates to a process for the preparation of thecompositions defined hereinbefore.

For this purpose, use is made of the organic compounds definedhereinbefore in the proportions required in the final alloy, saidcompounds being subjected to conventional techniques such asmelting/crystallization, melting/quenching, dissolution/evaporation,simultaneous sublimation, zone levelling or chemical inter-diffusion.The zone levelling technique is described more particularly by W. J.Kolkert, thesis 1974, Utrecht, Netherlands.

In one advantageous embodiment of the invention, to prepare the ALCALswhen all the Cns are liquid at ambient temperature, the required liquidsolution is formed by mixing and agitating the starting compounds usedin the proportions required in the alloy. When some or all of thestarting Cns are solid, the base products are dissolved in theappropriate proportions in a mutual solvent, for example ether,whereafter the solvent is evaporated (preferably in an inert gas flow).Alternatively, the weighed products are subjected to melting withagitation to ensure the homogeneity of the product, whereafter they arequenched.

As a variant, the compositions according to the invention are obtainedby separational methods, this having the advantage of using thebyproducts of the oil industry. A mixture of organic compoundscontaining the required composition is therefore subjected to anextraction stage in order to isolate said composition. When the mixturedoes not contain all the required organic compounds and/or in therequired proportions, the mixture is so treated as to increase itscontent of one or more constituents or to eliminate one or moreconstituents, as the case may be, until the required composition isobtained.

In a general way, the invention provides a number of acceptableformulations for the same temperature, enabling a selection to be madein accordance with the economic conditions and/or the availability ofthe base products.

The use of alloys enables the content to be selected and therefore theproper formulations to be sought for an optimum yield of the storedenergy and/or to meet demands as regards the temperature of utilizationand/or the required thermal window δ.

The work carried out has enabled the feasibility to be demonstrated fromat least three very advantageous functions, namely those of:

energy pick-up: molecular alloys enable considerable quantities of heatto be stored and restored practically at constant temperature;super-cooling is very low or even non-existant at the kg level, and evenat the mg level in the particular case of the ALCALS,

temperature smoothing: a space enclosed by a molecular alloy accordingto the invention can be maintained at approximately the temperature T(including in the transition range of the alloy). When the exteriorundergoes wide thermal fluctuations, the increase in temperature isreduced by the storage of heat in the form of latent heat, and anysudden drop in temperature would itself be minimized by the conversetransformation,

thermal screening: the molecular alloys can be used to slow down theeffect of a thermal wave.

The tests carried out (mg, g, kg levels) on the molecular alloysaccording to the invention have shown that these materials moreparticularly have excellent yields and thermal reliability and thattheir behaviour in thermal cycling is remarkable.

By way of example, a guarantee of 30 years of service life can beensured for day-to-day cycling of molecular alloys whose melting rangedoes not exceed 4° C. and the density of whose constituents is similar,which is the case with the alkanes. (All properties which the salinehydrates and conventional PCMs do not possess.)

The advantageous properties of the compositions defined hereinbefore areenjoyed by using them as phase change materials for the storage andrestoration of energy at a given level of temperature, for example, thatrequired for a particular application.

The invention relates therefore to the application as phase changematerial of the compositions formed by one or more molecular alloys, asdefined hereinbefore, said application being characterized in that useis made of a composition suitable for storing and restoring thermalenergy at a temperature T over a temperature range δ which strictly meetthe requirements of a given application.

The invention relates more particularly as PCMMAs, to the variouscompositions A_(xa) Z_(xz) defined hereinbefore in packaging appropriatefor a given application.

In these applications the basic principal rests on the fact that asituation of thermal dynamic non-equilibrium will be created and willnecessarily be followed by a path proceeding towards return toequilibrium. The PCMMA will either heat up, taking calories from theexternal medium to melt, or will cool down, restoring heat to theexternal medium to solidify. In both cases the transition will take theform of a long quasi-isotherm, its slope being gentler in proportion asδ is smaller.

As a result of the aforementioned characteristics, the PCMMAs accordingto the invention enable numerous needs to be met which have not hithertobeen satisfied in very varied fields. Examples are the agriculturalfeedstuffs and paramedical fields, and those connected with domesticprotection or utilizations.

Thus, in the agricultural feedstuffs field, all the problems of notbreaking the cold chain are concerned. The alloys according to theinvention can provide answers for the thermal protection and/ortransport of foodstuffs typically at between approximately -50° C. and+100° C.

In the range from approximately -50° C. to -10° C., these PCMMAs aremore particularly suitable for the bulk or individual transport offrozen products, or for their preservation. Their use therefore providesa bulwark against power cuts in freezers (commercial and domestic) byequipping the freezers with suitable PCMMAs.

The use according to the invention of the PCMMAs disclosed hereinbeforealso has great advantage in the temperature range of approximately -10°C. to +6° C. Thus it enables beverages and ices to be reliablytransported in the best conditions, for example, in ice-machine-typedevices, while keeping them at the required temperature. It is alsopossible to produce plates, dishes or dish supports ensuring therequired freshness.

The PCMMAs acceptable in this temperature range can also be used for thepreparation of refrigerated displays, as required, for example, by fishmerchants.

The PCMMAs according to the invention are also found to be very valuablein a temperature range between +6° C. and +16° C., which is thatrequired for foodstuffs which are not to be frozen but require storageand/or tasting at a relatively low temperature, for example, milkproducts, "fourth range products" and wines requiring to be "chambre".

The PCMMAs having a phase transition temperature higher than +16° C. andmore particularly up to +35° C. are advantageous for cooling certainother wines requiring a higher temperature for their consumption, and incooking for butter, sauce and yogurt containers or containers for sourdoughs or for the preservation of pastries or warmed tarts.

In higher temperature bands, between approximately +35° C. and +l00° C.,the PCMMAs defined hereinbefore can be used to ensure the thermalstabilization of devices, for example, fermenters, between +35° C. and+37° C., or for keeping them hot at a stable temperature up totemperatures of approximately +100° C.; for example cooked dishes (beingof great advantage to caterers, more particularly in home deliveries,cafeteriors, factory restaurants, large areas), dishes, dish supports,feeding bottles, plates of porridge, hot dishes, hot plates, meal trays,hot beverages.

An edible dye and/or flavouring will advantageously be associated withthe ALCAL to warn the customer if there has been an accidental leakageinto the foodstuff.

PCMMAs particularly suitable for these applications are formed bymolecular alloys having a thermal window not exceeding +2° C. orpreferably +1° C., or even less.

In this respect the ALCALs form particularly high-performance PCMMAswhich, moreover, are acceptable from the health aspect.

Different formulations of ALCALs having a transition temperature T inthe aforementioned ranges are given in the Examples. Of course, othersuitable formulations will readily be worked out with reference to thevarious parameters defined hereinbefore.

Staying with consecutive Cns (the same parity or not), the temperaturelevel plays a relatively decisive role as regards both the possibilitiesof crystallization and the δ attribute, all the more so since it goeshand in hand with the ε_(n) level.

This coefficient is used to assess the degree of molecular homeomorphismε_(k). ε_(n) is defined as follows ##EQU3##

where n is the difference n_(A) -n_(B) between the two molecules Cn_(A)and Cn_(B) to be compared, and n_(minimum) is the value of n of theshortest molecule.

At low temperature, advantageous embodiments are mainly derived fromeutectic mixtures of ALCAL (with δ=0° C.); as the temperature T rises,the limits of syncrystallization will increase and the high-attributeranges will become larger.

If non-consecutive Cns are selected, the roles of the Ts and the ε_(n) swill act in the same direction and be added to the T effect explainedhereinbefore. Thus, a considerable difference between the nAs and nZswill be associated with Ts which are higher and ε_(n) s which are lowerin proportion as T is lower. Conversely, the higher the value of T themore ALCALs having acceptable δs will be available with distant ns, withthe consequent extended possibility of having different formulations fora required T.sub.δ, since in that case the number of constituents can bemore readily increased.

Amongst the ALCALs, those will be mentioned which are formed moreparticularly by chains having C8 to C16, more particularly each of thesedoped alkanes, the consecutive or non-consecutive, possibly also dopedbinaries, ternaries, quaternaries or higher, with molar proportions suchthat the T.sub.δ values correspond strictly to the requirements.

The applications mentioned hereinbefore will advantageously be put intoeffect with ALCALs the majority of which contain chains having more than14 carbon atoms, possibly doped.

In the paramedical field the applications are also highly various andmore particularly cover a temperature range of between -80° C. and +75°C.

Sectors particularly involved comprise packaging, the protection ofinstruments, isothermal or control-temperature manipulations, the designof isothermal clothing, functional difficiencies and treatments ofsymptoms.

For applications relating to packaging and/or transport, withnon-breakage of the cold chain, advantageously PCMMAs are used which areacceptable at a given temperature, in a range of from approximately -80°C. to +16° C..

Thus, PCMMAs having a phase change at a temperature close to -80° C. areparticularly useful for the preservation and/or transport of bone graftsand/or tendons, plasma or serum.

PCMMAs acceptable at about -30° C. enable medicines or plasma to betransported in peak condition.

It is particularly advantageous to use PCMMAs acceptable around -20° C.for bone banks or for postmortem transport.

At higher temperatures, the PCMMAs ranging from approximately -10° C. to+6° C. offer great advantages. They are therefore advantageously usedmore particularly for transporting organs or amputated limbs and for thepreservation of red globules or organs.

PCMMAs having phase transitions in a range of between +6° C. and +16° C.are also very advantageous. They more particularly enable various kindof tissues or cells, such as corneal grafts or certain sperms to bepreserved. They also allow the preservation of vaccines which can thusbe transported and are available for patients at the site of anaccident.

In a temperature range above approximately +16° C., the PCMMAs are moreparticularly used for the transport of medicines.

Other applications in the paramedical field relate to isothermal orcontrol-temperature manipulations.

The PCMMAs according to the invention which have a transitiontemperature in a range of approximately -80° C. to -10° C. are moreparticularly suitable for cryomicrotomy, for example, for rachis orjoints. Those which have a transition temperature in a range ofapproximately -10° C. to +6° C. are very useful for the thawing ofplasma and cells, for haemodynamic investigation, the analysis of bloodgases, sterile tissue samplings, for example, of muscles or vessels, andcell cultures.

The PCMMAs having high transition temperatures, more particularly in atemperature range of +20° C. and above can be used, in increasing orderof temperature, for culture boxes and sample carriers (from +20° C. to+50° C.), in nerve electrophysiology (between +30° C. and +35° C.), forthe heating of transplants, for enzymatic tests (between +35° C. and+37° C.) and for the heating of blood prior to transfusion (towards +37°C.).

Other applications in the para-medical field relate to functionaldifficiencies and treatments of symptoms.

The PCMMAs according to the invention having a phase transition

in a range of approximately -10° C. to +6° C. are more particularlysuitable for pre- and post-operational care, more particularly inophthalmology (between 0° C. and +6° C.)

in a range of approximately +6° C. to +16° C., for veterinary treatmentand in cryotherapy, for example, to produce dressings for sprains and,

in a temperature range above +16° C. in cryotherapy, to obtainrefreshing effects and more particularly for certain forms of care(around +35° C.);

for the range above +37° C. they would be useful for incubators or forthe local or general heating of patients during operations or inpost-operative care (coverings, mattresses, for example, mattressesincorporating reinforcement in which the PCMMAs can be associated withother materials, such as fibrous or expanded materials, for reasons ofcomfort). Autonomy of operation will be prolonged by thermallyinsulating layers on the external surfaces not in contact with thepatient.

They will also be useful in heat treatments for example for rheumatism,or for producing latent heat packs.

To facilitate use in the family circle, more particularly in this kindof application, added to the PCMMA is a small amount of colouring agentof edible quality, so as not to disturb the health acceptability of thematerials. This feature enables the T of the application to be readilydefined (examples: blue for T=+6° C., green for +25° C., colourless for+35° C., yellow for +39° C., orange for +45° C. and red for +50° C.).The doctors will of course provide prescribe the use of any particulartemperature range.

Lastly, it will be noted that the availability of PCMMAs with a T.sub.δattribute at the required T offers practitioners the possibility ofcarrying out clinical tests at different temperatures in order todiscover the most suitable ones.

In these applications in the paramedical field with the differenttemperature levels in question, it is more particularly advantageous touse PCMMAs formed by AL-CALs, possibly containing functional groups.

The PCMMAs according to the invention also enable the problems to besolved which are connected with the safety and/or protection ofproducts, installation and premises. These applications relate to a widetemperature range typically extending from -80° C. to +200° C..

They provide a very advantageous solution more particularly for

the transport of flammable and/or dangerous chemical products at lowtemperature,

the protection of electrical installations and electronic or informationsystems, in which they are possibly coupled with alarm systems (thetemperature ranges for this kind of use are very varied and may extendup to +200° C. and more, for example, in the case of fires), aparticularly advantageous temperature range being between +70° C. and+90° C.,

protection against sudden power cuts, avoiding the necessity of verycostly contracts concerning non-interruptable power supply ininstallations requiring iso-thermal maintenance, for example, fruit orvegetable ripening units or fermentation vats.

The PCMMAs according to the invention are also particularly useful inthe field of protection as a solution to energy saving problems. Theyform highly efficient protection means, for example, "cumulus", hotbaths, giving extra comfort, thermal reservoirs for heat pumps (notchesfrom +45° C. to +55° C. for hot sources and from +3° C. to +10° C. forcool sources), cold thermal screens for large assemblies (range from +4°C. to +8° C.), or for domestic heating (by latent heat), beingintegrable as a decorative element (transparent or opaque objects, forexample, statues).

They can also be used in cultures, more particularly ensuring theproduction of plant roots in glasshouses, avoiding the complete heatingof the glasshouse, or in sample carriers.

In domestic or industrial applications, the PCMMAs according, to theinvention will be advantageously used for articles independently used inthe home or outside, such as hair curlers, irons, feeding bottles, forexample when camping.

They also enable increasing or decreasing thermal gradients to bereadily produced which can be as strong or weak as required and cantherefore be used for regulating enclosures in which there is a thermalgradient such as those, for example, required in growing crystals.

In the various applications mentioned hereinbefore, for the productionof the PCMMAs use is advantageously made of substituted orunsubstituted, possibly doped ALCALs, and also of the cyclic andheterocyclic compounds as defined hereinbefore. Other advantageousmolecular alloys contain hydrocarbon chains which differ from thealkanes with functional groups. Yet other molecular alloys are formed bypolymer chains.

Clearly, in the various applications of the PCMMAs, the method of usecan be diversified; a PCMMA can be used on its own (or) associated withone or more other PCMMAs and/or PCMs so as to form multiple layers(which can advantageously be used to form temperature gradients).

In numerous applications the PCMMA operates in conjunction with anenergy source.

In general, the invention supplies the means for producing the mostsuitable materials for a given application. Such production is all themore facilitated by the fact that the compositions according to theinvention are malleable. The liquid compositions are thus perfectlysuited and are solidified in an appropriate shape.

The PCMMAs are packaged in structures adapted to their use.

In general, the parkaging comprise a double wall of a material having ahigh heat insulation capacity, at the very least the wall in contactwith the external medium when the two walls are produced using differentmaterials.

Suitable materials include glass, metals, the material commerciallyavailable under the trade mark PLASTISHIELD_(R), based on glass andpolymers, and also plastics materials and expanded polymers with closedcells.

The following may be mentioned by way of example: the polyolefines, suchas high density (HDPE) or low density (LDPE) polyethylene orpolypropylene (PP), the polyesters, more particularly ethylenepolyterephthalate or acrylates, the styrenes, such as polystyrene (PSE)or expanded polystyrene (ES), or acrylonitrile-butadiene-styrene (ABS),the polyamides (PA), the polyvinyls, such as polyvinyl chloride (PVC),the fluorinated polymers, such as polytetrafluoroethylene (PTFE).

These materials allow smooth, undulating or alveolated surfaces to beproduced.

If necessary they can be reinforced, for example, with struts, to ensurethat the structure behaves satisfactorily.

For their shaping, the usual plastics converter and processor techniquesare used; thus, injection, injection/blowing, injection/blowing bybiorientation, extrusion/blowing, blowing or rotational moulding methodsare used to product flasks, drums, bottles, flagons, pitchers, kegs,casks, vats, reservoirs, jars, boxes.

Thermoforming or injection are used to produce alveolated ornon-alveolated, reinforced or non-reinforced pots, goblets, troughs,bell jars, meal trays and also clipping devices.

Advantageously extrusion or calendering techniques are used when thepackaging does not require a double wall, for example, to producereceptacles such as pouches, flexible doses, cartridges, sheaths, bags,sachets, briquettes.

The packaging is filled with the PCMMA using the liquid or pulverulentcomposition.

If necessary liquid alloy can be preshaped, placed in a matrix andsolidified using liquid nitrogen. In that case it can be transferred inthe solid state to the final packaging.

The invention will be illustrated hereinafter by examples of thepreparation of molecular alloys and their applications as PCMMAs.

In the examples reference is made to FIGS. 1 and 9, which are diagramsgiving the attributes δ of various ternary molecular alloys.

Characterization of the materials:

1. X-ray analysis (Guinier-Lenne, Guinier-Simon) to define the numberand nature of the phases present in relation to temperature, demonstratethe phase changes and prove that prior to melting the materials actuallytake the form of alloys (and not mixtures of starting compounds).

2. Differential calorimetric analysis (AED, DSC): for the precisedetermination of the pertinent temperatures and the associatedenthalpies, observing the two following criteria:

preliminary calibration carried out strictly in the same experimentalconditions as these of the analyses.

use of the AED or DSC signals by the "shape factors method" developed byHaget et al, Calorim. Anal. Therm. (1987), 18, 255, and Courchinoux etal., J. Chim. Phys. (1989), 86, 3, 561.

The following Examples 1 to 5 relate to the ALCALS, Examples 6 to 9 tomolecular alloys containing or formed by chains having an acid function,and Examples 10 to 12 to applications of the molecular alloys accordingto the invention. (It will be noted that in the values of T.sub.δ and δgiven in the examples, T and δ are in ° C.).

Examples 1 to 7 concern respectively:

Example 1: the formulation of doped ALCALs,

Example 2: the formulation of doped binary ALCALs,

Example 3: the formulation of doped ternary ALCALs and higher.

Example 4: study of the evolution of binary ALCALs,

binary ALCALS of the same parity [1) consecutive; 2) non-consecutive],

binary ALCALs with different parity [1) consecutive; 2)non-consecutive],

Example 5: ternary ALCALs:

a) study of the evolution of ALCALs [1) consecutive; 2) not directlyconsecutive],

b) various formulations of ternary ALCALs (1 to 9).

Remarks concerning the alcanes.

When 8≦ n ≦20, prior to melting the alcanes having odd ns (Cni) are ofhexagonal form, those having even ns (Cnp) being triclinic.

When 21≦n ≦43, all the alcanes are hexagonal prior to melting.

Lastly, when n≧44, all the alcanes are orthorhombic prior to melting.

General method of preparation.

When some or all the alcanes which are used are solid, first thestarting alcanes are dissolved in suitable proportions in a commonsolvent, for example, ether, whereafter the solvent is evaporated,preferably in a flow of an inert gas, for example nitrogen.Alternatively, the products are melted and agitated, to produce ahomogeneous mixture, whereafter they are soaked.

EXAMPLE 1

Formulations of doped alcanes.

Table 1, which follows, presents formulations of doped alcanes. For eachalloy formulation the transition temperature T is indicated in ° C., thethermal window δ in ° C. and the enthalpy variation H in J/g.

                  TABLE 1                                                         ______________________________________                                        Cn    Formulations    T(°C.)                                                                          δ(°C.)                                                                   H(J/g)                                 ______________________________________                                        C8    C8.sub.0.980 C10.sub.0.020                                                                    -57.2    1.4    170                                       C9 C9.sub.0.995 C10.sub.0.005 -53.0 1.3 117                                   C1O C10.sub.0.990 C11.sub.0.010 -29.0 1.2 196                                 C11 C11.sub.0.998 C12.sub.0.001 C13.sub.0.001 -25.0 1.3 141                   C12 C12.sub.0.993 C11.sub.0.004 C13.sub.0.004 -9.4 1.2 210                    C13 C13.sub.0.998 C11.sub.0.001 C12.sub.0.001 -4.7 0.6 162                    C14 C14.sub.0.999 C13.sub.0.001 +5.9 1.5 216                                  C15 C15.sub.0.994 C14.sub.0.001 C16.sub.0.005 +10.0 0.6 159                   C16 C16.sub.0.996 C15.sub.0.003 C17.sub.0.001 +17.9 1.0 227                   C17 C17.sub.0.998 C15.sub.0.001 C16.sub.0.001 +22.2 0.5 168                   C18 C18.sub.0.994 C19.sub.0.006 +28.4 0.9 232                                 C19 C19.sub.0.980 C20.sub.0.020 +32.3 0.9 168                                 C20 C20.sub.0.980 C19.sub.0.020 +36.4 5.0 240                                 C20 C20.sub.0.994 C19.sub.0.006 +36.5 1.6 241                                 C21 C21.sub.0.997 C23.sub.0.003 +39.9 0.3 156                                 C22 C22.sub.0.980 C21.sub.0.020 +43.3 0.9 152                                 C22 C22.sub.0.997 C21.sub.0.003 +43.8 0.9 152                                 C23 C23.sub.0.996 C22.sub.0.002 C24.sub.0.002 +47.5 0.2 158                   C23 C23.sub.0.980 C24.sub.0.020 +48.2 0.8 160                                 C24 C24.sub.0.950 C22.sub.0.050 +50.1 0.2 157                                 C24 C24.sub.0.930 C20.sub.0.050 C22.sub.0.020 +50.5 1.1 158                   C24 C24.sub.0.950 C26.sub.0.050 +50.9 0.2 158                                 C25 C25.sub.0.992 C24.sub.0.005 C26.sub.0.003 +53.8 0.2 161                   C26 C26.sub.0.998 C24.sub.0.002 +56.9 0.1 161                                 C26 C26.sub.0.999 C25.sub.0.001 +56.9 0.1 161                               ______________________________________                                    

An examination of this Table shows that the different doped formulationsstudied have a transition over a narrow temperature range which isalways less than 2° C., and does not even exceed 1° C. for the majority,the oHs being mainly higher than 150 J/g and even greater than 200 J/gin certain cases.

EXAMPLE 2

Formulations of doped binary ALCALs.

Table 2 shows the characteristics of doped binary alloys.

                  TABLE 2                                                         ______________________________________                                        Examples:                                                                                                   T     δ                                                                             H                                     Cn-Cn Formulation (°C.) (°C.) (J/g)                           ______________________________________                                        C 8-C10                                                                              C8.sub.0.930 C10.sub.0.060 C9.sub.0.010                                                          -57.7   2.8  170                                      C10-C11 C10.sub.0.690 C11.sub.0.300 C12.sub.0.010 -35.9 2.1 137                                                     C10-C11 C10.sub.0.490 C11.sub.0.49                                           0 C12.sub.0.020 -33.2 4.2 129                                                  C10-C11 C10.sub.0.310 C11.sub.0.68                                           0 C12.sub.0.010 -30.4 4.2 125                                                  C11-C12 C11.sub.0.880 C12.sub.0.10                                           0 C13.sub.0.020 -24.9 1.1 141                                                  C11-C12 C11.sub.0.490 C12.sub.0.49                                           0 C13.sub.0.020 -21.6 2.0 134                                                  C12-C13 C12.sub.0.690 C13.sub.0.30                                           0 C11.sub.0.010 -13.5 2.7 146                                                  C12-C13 C12.sub.0.480 C13.sub.0.48                                           0 C11.sub.0.040 -11.8 2.2 146                                                  C12-C13 C12.sub.0.200 C13.sub.0.78                                           0 C11.sub.0.020 -8.0 2.4 150                                                   C13-C15 C13.sub.0.780 C15.sub.0.20                                           0 C14.sub.0.020 -5.0 1.0 144                                                   C13-C14 C13.sub.0.690 C14.sub.0.30                                           0 C15.sub.0.010 -3.9 1.4 152                                                   C13-C14 C13.sub.0.485 C14.sub.0.49                                           0 C15.sub.0.025 -2.5 1.8 152                                                   C13-C15 C13.sub.0.530 C15.sub.0.45                                           0 C14.sub.0.020 0 7.0 148                C14-C16 C14.sub.0.790 C16.sub.0.200 C15.sub.0.010 +2.9 2.0 159                C14-C16 C14.sub.0.890 C16.sub.0.100 C15.sub.0.010 +3.2 1.9 164                C14-C15 C14.sub.0.400 C15.sub.0.570 C13.sub.0.030 +5.2 3.9 147                C13-C15 C13.sub.0.200 C15.sub.0.790 C14.sub.0.010 +6.0 8.0 159                C14-C15 C14.sub.0.260 C15.sub.0.700 C16.sub.0.040 +7.7 2.0 155                C14-C16 C14.sub.0.410 C16.sub.0.580 C15.sub.0.010 +8.8 4.9 148                C15-C16 C15.sub.0.840 C16.sub.0.130 C14.sub.0.030 +9.5 1.0 153                C15-C16 C15.sub.0.840 C16.sub.0.150 C14.sub.0.010 +10.5 0.8 150                                                     C15-C16 C15.sub.0.640 C16.sub.0.33                                           0 C14.sub.0.030 +10.7 2.0 152                                                  C15-C16 C15.sub.0.690 C16.sub.0.30                                           0 C14.sub.0.010 +11.2 1.3 156                                                  C15-C17 C15.sub.0.685 C17.sub.0.30                                           0 C16.sub.0.015 +11.3 1.3 146                                                  C15-C16 C15.sub.0.490 C16.sub.0.50                                           0 C14.sub.0.010 +12.3 1.7 157                                                  C15-C17 C15.sub.0.480 C17.sub.0.50                                           0 C16.sub.0.020 +14.0 3.0 150                                                  C14-C16 C14.sub.0.100 C16.sub.0.89                                           0 C15.sub.0.010 +16.0 3.2 175                                                  C15-C17 C15.sub.0.300 C17.sub.0.69                                           0 C16.sub.0.010 +17.0 4.4 154                                                  C16-C18 C16.sub.0.690 C18.sub.0.29                                           0 C17.sub.0.020 +18.0 1.9 170                                                  C16-C18 C16.sub.0.550 C18.sub.0.44                                           0 C17.sub.0.010 +19.8 2.0 165                                                  C16-C17 C16.sub.0.300 C17.sub.0.68                                           5 C15.sub.0.010 C18.sub.0.005                                                 +19.8 1.5 160                            C15-C17 C15.sub.0.100 C17.sub.0.890 C16.sub.0.010 +20.4 2.9 158                                                     C16-C17 C16.sub.0.100 C17.sub.0                                              885 C15.sub.0.005 C18.sub.0.010                                               +21.3 1.1 165                            C17-C18 C17.sub.0.300 C18.sub.0.690 C19.sub.0.010 +25.7 1.2 159                                                     C18-C22 C18.sub.0.870 C22.sub.0.10                                           0 C20.sub.0.030 +27.8 1.8 164                                                  C18-C19 C18.sub.0.800 C19.sub.0.17                                           0 C17.sub.0.030 +27.9 1.5 156                                                  C18-C20 C18.sub.0.780 C20.sub.0.20                                           0 C19.sub.0.020 +28.3 1.8 155                                                  C18-C19 C18.sub.0.780 C19.sub.0.20                                           0 C20.sub.0.020 +28.4 1.5 155                                                  C18-C20 C18.sub.0.780 C20.sub.0.20                                           0 C22.sub.0.020 +28.5 2.0 154                                                  C18-C19 C18.sub.0.580 C19.sub.0.40                                           0 C17.sub.0.020 +28.8 1.6 156                                                  C18-C19 C18.sub.0.580 C19.sub.0.39                                           0 C20.sub.0030 +29. 1.6 156                                                    C18-C22 C18.sub.0.700 C22.sub.0.28                                           0 C20.sub.0.020 +30.8 3.9 139                                                  C18-C20 C18.sub.0.540 C20.sub.0.45                                           0 C19.sub.0.010 +30.8 1.9 146                                                  C18-C20 C18.sub.0.530 C20.sub.0.44                                           0 C22.sub.0.030 +30.9 2.0 146                                                  C18-C20 C18.sub.0.190 C20.sub.0.80                                           0 C22.sub.0.010 +33.9 2.0 150                                                  C18-C20 C18.sub.0.200 C20.sub.0.79                                           0 C19.sub.0.010 +33.9 2.0 150                                                  C19-C20 C19.sub.0.300 C20.sub.0.68                                           0 C21.sub.0.020 +35.2 0.9 151                                                  C19-C21 C19.sub.0.290 C21.sub.0.69                                           0 C20.sub.0.020 +35.5 1.2 151                                                  C20-C22 C20.sub.0.770 C22.sub.0.20                                           0 C18.sub.0.030 +37.5 0.9 146                                                  C20-C22 C20.sub.0.794 C22.sub.0.20                                           0 C19.sub.0.004 C21.sub.0.002                                                 +37.6 0.8 146                            C20-C22 C20.sub.0.8.00 C22.sub.0.170 C21.sub.0.030 +37.8 0.8 146                                                    C20-C22 C20.sub.0.780 C22.sub.0.20                                           0 C24.sub.0.020 +38.0 0.8 145                                                  C20-C24 C20.sub.0.870 C24.sub.0.11                                           0 C22.sub.0.020 +38.6 1.2 145                                                  C20-C22 C20.sub.0.480 C22.sub.0.49                                           0 C21.sub.0.030 +39.7 1.5 148                                                  C20-C22 C20.sub.0.471 C22.sub.0.52                                           4 C19.sub.0.003 C21.sub.0.002                                                 +39.8 1.3 148                            C20-C22 C20.sub.0.500 C22.sub.0.480 C24.sub.0.020 +40.0 1.5 147                                                     C20-C22 C20.sub.0.400 C22.sub.0.58                                           0 C18.sub.0.020 +40.1 1.5 147                                                  C20-C22 C20.sub.0.376 C22.sub.0.62                                           0 C19.sub.0.002 C21.sub.0.002                                                 +40.3 1.2 147                            C20-C22 C20.sub.0.380 C22.sub.0.600 C24.sub.0.020 +40.6 1.4 147                                                     C20-C22 C20.sub.0.300 C22.sub.0.69                                           0 C21.sub.0.010 +41.2 1.4 147                                                  C20-C22 C20.sub.0.279 C22.sub.0.71                                           7 C19.sub.0.002 C21.sub.0.002                                                 +41.3 1.2 147                            C20-C22 C20.sub.0.180 C22.sub.0.800 C18.sub.0.020 +41.8 1.1 147                                                     C21-C22 C21.sub.0.490 C22.sub.0.49                                           0 C23.sub.0.020 +41.8 0.6 150                                                  C20-C22 C20.sub.0.184 C22.sub.0.81                                           2 C19.sub.0.001 C21.sub.0.003                                                 +42.0 0.9 147                            C20-C22 C20.sub.0.090 C22.sub.0.900 C21.sub.0.010 +42.8 0.9 150                                                     C20-C22 C20.sub.0.093 C22.sub.0.90                                           3 C19.sub.0.001 C21.sub.0.003                                                 +42.9 1.0 150                            C21-C23 C21.sub.0.580 C23.sub.0.400 C22.sub.0.020 +43.3 1.3 152                                                     C22-C24 C22.sub.0.700 C24.sub.0.28                                           0 C20.sub.0.020 +45.2 0.8 153                                                  C22-C23 C22.sub.0.490 C23.sub.0.50                                           0 C24.sub.0.010 +45.7 0.5 155                                                  C22-C24 C22.sub.0.700 C24.sub.0.28                                           0 C23.sub.0.020 +45.7 0.9 152                                                  C22-C24 C22.sub.0.680 C24.sub.0.30                                           0 C26.sub.0.020 +45.7 0.8 153                                                  C22-C24 C22.sub.0.300 C24.sub.0.68                                           0 C20.sub.0.020 +48.1 0.9 155                                                  C22-C24 C22.sub.0.280 C24.sub.0.70                                           0 C23.sub.0.020 +48.4 0.9 156                                                  C22-C24 C22.sub.0.300 C24.sub.0.68                                           0 026.sub.0.020 +48.6 0.9 155                                                  C23-C24 C23.sub.0.470 C24.sub.0.50                                           0 C22.sub.0.030 +48.9 0.5 158                                                  C22-C24 C22.sub.0.050 C24.sub.0.93                                           0 C23.sub.0.020 +50.2 0.4 158                                                  C22-C26 C22.sub.0.500 C26.sub.0.49                                           0 C24.sub.0.010 +50.2 2.6 157                                                  C24-C26 C24.sub.0.900 C26.sub.0.08                                           0 C20.sub.0.020 +50.2 0.4 158                                                  C24-C25 C24.sub.0.500 C25.sub.0.49                                           0 C26.sub.0.010 +51.7 0.4 159                                                  C24-C26 C24.sub.0.490 C26.sub.0.50                                           0 C20.sub.0.010 +52.2 0.9 158                                                  C23-C25 C23.sub.0.100 C25.sub.0.89                                           0 C24.sub.0.010 +53.0 0.9 161                                                  C24-C26 C24.sub.0.490 C26.sub.0.50                                           0 C22.sub.0.010 +53.5 0.9 162                                                  C26-C32 C26.sub.0.800 C32.sub.0.19                                           0 C30.sub.0.010 +57.3 2.0 160                                                  C28-C32 C28.sub.0.790 C32.sub.0.20                                           0 C30.sub.0.010 +62.4 0.4 160                                                  C30-C32 C30.sub.0.100 C32.sub.0.88                                           0 C31.sub.0.010 C33.sub.0.010                                                 +66.2 0.5 159                            C35-C36 C35.sub.0.890 C36.sub.0.090 C37.sub.0.020 +75.2 0.4 160                                                     C44-C50 C44.sub.0.765 C50.sub.0.21                                           0 C46.sub.0.010 C48.sub.0.015                                                 +86.7 0.7 223                            C44-C50 C44.sub.0.490 C50.sub.0.485 C46.sub.0.005 C48.sub.0.020 +87.4                                              0.5 220                                  C44-C50 C44.sub.0.395 C50.sub.0.585 C46.sub.0.005 C48.sub.0.015 +89.2                                              1.5 225                                  C46-C50 C46.sub.0.100 C50.sub.0.890 C44.sub.0.010 +91.9 0.6 215             ______________________________________                                    

EXAMPLE 3

Formulations of doped ternary and higher ALCALs.

Table 3 shows the characteristics of doped ternary or higher alloys.

                                      TABLE 3                                     __________________________________________________________________________    Alcanes  Formulation        T (°C.)                                                                    δ                                                                          H (J/g)                                    __________________________________________________________________________    C12-C13-C14                                                                            C12.sub.0.130 C13.sub.0.607 C14.sub.0.262 C11.sub.0.001                                          -6.2                                                                              4.8                                                                              130                                          C15-C16-C17 C15.sub.0.660 C16.sub.0.240 C17.sub.0.070 C18.sub.0.030                                            +11.3 2.0 152                                C14-C15-C16 C14.sub.0.214 C15.sub.0.226 C16.sub.0.558 C13.sub.0.001                                            C17.sub.0.001 +8.5 2.3 152                   C14-C15-C16 C14.sub.0.350 C15.sub.0.430 C16.sub.0.160 C17.sub.0.040                                            C18.sub.0.020 +7.1 2.7 146                   C14-C15-C16 C14.sub.0.320 C15.sub.0.380 C16.sub.0.250 C17.sub.0.040                                            C18.sub.0.010 +7.5 2.5 144                   C14-C15-C16 C14.sub.0.280 C15.sub.0.350 C16.sub.0.320 C17.sub.0.040                                            C18.sub.0.010 +8.3 3.0 143                   C14-C15-C16-C18 C14.sub.0.310 C15.sub.0.370 C16.sub.0.140 C17.sub.0.040                                        C18.sub.0.140 +7.5 3.4 127                   C14-C15-C16-C17 C14.sub.0.290 C15.sub.0.350 C16.sub.0.130 C17.sub.0.130                                        C18.sub.0.010 +8.6 4.1 146                   C15-C16-C17 C15.sub.0.366 C16.sub.0.462 C17.sub.0.167 C18.sub.0.005                                            +13.5 2.0 154                                C15-C16-C17 C15.sub.0.272 C16.sub.0.069 C17.sub.0.649 C18.sub.0.010                                            +17.3 3.9 150                                C15-C16-C17 C15.sub.0.065 C16.sub.0.067 C17.sub.0.848 C18.sub.0.020                                            +20.6 2.8 160                                C18-C20-C22 C18.sub.0.850 C20.sub.0.065 C22.sub.0.065 C16.sub.0.020                                            +27.5 2.0 150                                C18-C20-C22 C18.sub.0.625 C20.sub.0.230 C22.sub.0.130 C24.sub.0.015                                            +30.0 1.9 142                                C18-C20-C22 C18.sub.0.330 C20.sub.0.310 C22.sub.0.330 C24.sub.0.030                                            +36.0 3.7 139                                C20-C22-C26 C20.sub.0.620 C22.sub.0.230 C26.sub.0.130 C24.sub.0.020                                            +39.5 1.8 143                                C20-C22-C24 C20.sub.0.340 C22.sub.0.320 C24.sub.0.310 C23.sub.0.030                                            +43.4 2.8 147                                C22-C24-C26 C22.sub.0.450 C24.sub.0.360 C26.sub.0.160 C25.sub.0.020                                            C27.sub.0.010 +47.7 1.1 154                  C22-C24-C26 C22.sub.0.170 C24.sub.0.640 C26.sub.0.160 C25.sub.0.030                                            +50.3 0.8 156                                C44-C46-C48-C50 C44.sub.0.350 C46.sub.0.350 C48.sub.0.080 C50.sub.0.200                                        C47.sub.0.020 +86.9 0.6 220                  C44-C46-C50 C44.sub.0.390 C46.sub.0.390 C50.sub.0.190 C48.sub.0.030                                            +87.2 0.5 224                              __________________________________________________________________________

EXAMPLE 4

Binary ALCALs. Study of evolution.

In this and the following Examples, the degree of molecularhomeomorphism ε_(k) is determined by the coefficient ε_(n) definedhereinbefore:

where n is the difference n_(A) -n_(B) between the two molecules Cn_(A)and Cn_(B) to be compared, and n_(minimum) is the value of n of theshortest molecule.

I Binary ALCALs of the same parity:

A and Z are both taken from the even alcanes or both taken from the oddalcanes.

1 Consecutive ALCALs

They are of type Cnp-C(np+2) or of the type Cni-C(ni+2). The two typeshave very similar behaviour. Four cases may be generally distinguished:

First case: n≦12; in this case ε_(n) ≦0.80 and T≧20° C. (T being thedifference between the melting temperatures of the two ALCALs formingthe binary).

Miscibility is incomplete; there are eutectics.

Examples:

C8-C10: ε_(n) =0.75; T=27.1° C.,

A eutectic is formed for the global composition 82% C8+18% C10

T=-62° C., δ=0, G=190 J/g.

Compositions are obtained which form advantageous PCMMAs for C8_(1-x)C10_(x) with x≦0.15, more particularly with

x=0.05 (T=-57.5° C., δ=2.8, and H=170 J/g)

x=0.11 (T=-59.3° C., δ=1.6, and H=180 J/g).

C10-C12: ε_(n) =0.80, T=20.1° C.: a eutectic is formed for a globalcomposition 80% C10+20% C12 (T=-38° C., δ=0, H=195 J/g).

Second case: 12≦n≦18; we then have 0.80 ε_(n) ≦0.88 and 10≦T<20.

The greater the value of n, the greater the miscibility (in theconcentration field) and the narrower the loops will become.

C12-C14: ε_(n) =0.83; T=15.5° C.

Miscibility is extended, but the loops are wide.

Satisfactory alloys are obtained with pure components, more particularlyin the C12 direction. (Herein-after the thermal window δ concerning aconcentration range are given with a global attribute taken equal to aninteger: 1 when δ≦1, 2 when 1<δ≦2, 4 when 2<δ≦4. On the other hand, forthe particular examples δ is given with its true value).

Description of the alloys C12_(1-x) C14_(x) acceptable according to theinvention with

0≦x<0.05: δ=2

0.05 ≦x<0.15: δ=4,

for example x=0.11: T=-12.0° C., δ=3.1, H=175 J/g

0.15≦x≦0.22: δ=2,

for example x=0.19: T=-14.2° C., δ=1.7, H=159 J/g

0.92≦x≦1: δ=4,

for example x=0.95: T=+5.0° C., δ=3.6, H=205 J/g

C13-C15: ε_(n) =0.85; T =15.5° C.,

miscibility in all proportions is observed, but wide loops, except inthe direction of C13.

Description of the acceptable alloys C13_(1-x) C15_(x) :

0≦x<0.20:δ=1

0.20≦x<0.30:δ=2,

for example x=0.200: T=-5.1° C., δ=0.9, H=144 J/g

0.30≦x<0.40: δ=4,

0.40≦x<0.95: δ=6,

for example x=0.464: T=-0.5° C., δ=6.0, H=148 J/g

x=0.794: T=+6.1° C., δ=7.8, H=159 J/g

0.95≦x≦1: δ=4,

with doping:

C13₀,78 C15₀,20 C14₀,02 : T=-5.0° C., δ=1.0, H=144 J/g

C13₀,53 C15₀,45 C14₀,02 : T=0.0° C., δ=7.0,H=148 J/g

C14-C16: ε_(n) =0.86; T=12.3° C., Whatever the proportions may be, totalmiscibility is observed when the chains are mixed. The width of the loopvaries with the zones.

Amongst the alloys C14_(1-x) C16_(x), the results obtained are presentedwith different values of x.

0≦x≦0.30: δ=2

for example x=0.10: T=+3.2° C., δ=1.9, H=164 J/g

x=0.20: T=+2.9° C., δ=2H=147 J/g

0.30≦x<0.47: δ=4,

for example x=0.35: T=+4.7° C., δ=2.8, H=137 J/g

0.47≦x<0.80: δ=6,

for example x=0.60: T=+9.0° C., δ=4.9, H=148 J/g

0.80≦x<0.95: δ=4,

for example x=0.90: T=+16.1° C., δ=3.2, H=176 J/g

0.95≦x≦1: δ=2

Formulations of doped C14-C16:

C14₀.790 C16₀.200 C15₀.010 :T=+2.900, δ=2.0, H=159 J/g

C14₀.890 C16₀.100 C15₀.010 :T=+3.2° C., δ=1.9,H=164 J/g

C14₀.410 C16₀.580 C15₀.010 :T=+8.8° C., δ=4.9,H=148 J/g

C14₀.100 C16₀.890 C15₀.010 :T=+16.0° C., δ=3.2, H=175 J/g

C15-C17 : ε_(n) =0.57 ;T=12.0° C.

Total miscibility for C¹⁵ _(1-x) C¹⁷ _(x), but δ is wider to the rightof centre.

0≦x<0.20 δ=1

0.20≦x<0.425 δ=2

for example, x=0.30: T=+11.3° C., δ=1.2, H=146 J/g

0.425≦x<0.57 δ=4

for example, x=0.50 : T=+14.1° C., δ=2.9, H=156 J/g

0.57≦x<0.80 δ=6

for example, x=0.70 : T=+17.0° C., δ=4.4, H=154 J/g

0.80≦x<0.95 δ=4

for example, x=0.90 : T=+20.2° C., δ=2.9, H=158 J/g

0.95≦x≦1 δ=2

Doped formulations:

C15₀.685 C17₀.300 C16₀.015 : T=+11.3° C.,δ=1.3,H=146 J/g

C15₀.480 C17₀.500 C16₀.020 : T=+14.0° C.,δ=3.0,H=150 J/g

C15₀.300 C17₀.690 C16₀.010 : T=+17.0° C.,δ=4.4,H=154 J/g

C15₀.100 C17₀.890 C16₀.010 : T=°20.4° C., δ=2,9, H=158 J/g

C16-C18 : ε_(n) =0.88 ; T=10.0° C.

All the formulations C16_(1-x) C18_(x) have δ≦4. The restrictions for0.03<x<0.10 and 0.75<x<0.97 correspond to widenings of the solid-liquidloop related to interference with solid-solid loops (this phenomenonappears in a number of other binary alloys, whether the pure alcanesthemselves have a transition, or whether the transition is induced bythe other Cn, as is the case in this binary)

0.10≦x<0.50: δ=2

0.50≦x≦0.75: δ=4

Doped formulations:

C16₀.690 C18₀.290 C17₀.020 :T+18.0° C., δ=1.9, H=170 J/g

C16₀.550 C18₀.440 C17₀.010 :T=+19.8° C., δ=2.0, H=165 J/g

Third case:

18≦n≦22; in that case we have 0.88<ε_(n) ≦0.90 and 7° C. <T<10° C.

Total miscibility; all the molecular alloys have δ≦2; merely a very weakperturbation is felt, due to the possible solid-solid transition (C20 inparticular).

C18-C20: ε_(n) =0.89; T=8.6° C.

The following results were obtained with C18_(1-x) C20_(x) :

0≦x<0.03 (doping) : δ=1

0.03≦x<0.05 with transition effect of C18

0.05≦x<0.90: δ=2

for example:

    ______________________________________                                        x = 0.20 : T = +28.2° C.                                                                 δ = 1.6                                                                          H = 154 J/g                                          x = 0.45 : T = +30.6° C. δ = 1.8   H = 146 J/g                   x = 0.80 : T = +33.7° C. δ = 2.0   H = 150 J/g                 ______________________________________                                    

0.90≦x<0.97 with transition effect of C20

0.97≦x≦1: δ=1

The following results were obtained with doped binaries:

    ______________________________________                                        C18.sub.0.78 C20.sub.0.20 C19.sub.0.02                                                         T = +28.3° C.                                                                     δ = 1.8                                       C18.sub.0.78 C20.sub.0.20 C22.sub.0.02 T = +28.5° C. δ =                                   2.0                                                 C18.sub.0.54 C20.sub.0.45 C19.sub.0.01 T = +30.8° C. δ =                                   1.9                                                 C18.sub.0.53 C20.sub.0.44 C22.sub.0.03 T = +30.9° C. δ =                                   2.0                                                 C18.sub.0.19 C20.sub.0.80 C22.sub.0.01 T = +33.9° C. δ =                                   2.0                                                 C18.sub.0.20 C20.sub.0.79 C19.sub.0.01 T = +33.9° C. δ =                                   2.0                                               ______________________________________                                    

We therefore noticed that the doped or undoped binaries C18-C20 respondsubstantially in the same manner. Thus, the doping of a given PCMMAenables T to be adjusted without affecting δ (or H) for a value of x.

C19-C21 : ε_(n) =0.89; T=8.4° C.

C19_(1-x) C21_(x)

0≦x<0.20: δ=1

0.20≦x<0.90: δ=2

0.90≦x≦1: δ=1

With doping (example)

C19₀.290 C21₀.690 C20₀.020 : T=+35.5° C. δ=1.2 H=151 J/g

C20-C22: ε_(n) =0.90, T=7.6° C.

We note that the loop becomes thinner in comparison with those of thepreceding alloys. A solid-solid transition effect of C20 is observedonly between 0.02<x<0.05.

With

x<0.40, we obtain δ=1

0.40≦x<0.75: δ=2

0.75≦x≦1: δ=1

Examples of doped formulations, classified by T (the H are practicallyequal to 147 J/g)

    ______________________________________                                        C20.sub.0.094 C22.sub.0.200 C19.sub.0.004 C21.sub.0.002                                           T = +37.6° C.                                                                     δ = 0.8                                    C20.sub.0.80 C22.sub.0.17 C21.sub.0.03 T = +37.8° C. δ =                                      0.8                                              C20.sub.0.78 C22.sub.0.20 C24.sub.0.02 T = +38.0° C. δ =                                      0.8                                              C20.sub.0.48 C22.sub.0.49 C21.sub.0.03 T = +39.7° C. δ =                                      1.5                                              C19.sub.0.003 C20.sub.0.471 C21.sub.0.002 C22.sub.0.524 T = +39.8.degree                                   . C. δ = 1.3                               C20.sub.0.50 C22.sub.0.48 C24.sub.0.02 T = +40.0° C. δ =                                      1.5                                              C19.sub.0.002 C20.sub.0.376 C21.sub.0.002 C22.sub.0.620 T = +40.3.degree                                   . C. δ = 1.2                               C20.sub.0.38 C22.sub.0.60 C24.sub.0.02 T = +40.6° C. δ =                                      1.4                                              C20.sub.0.30 C22.sub.0.69 C21.sub.0.01 T = +41.2° C. δ =                                      1.4                                              C19.sub.0.002 C20.sub.0.279 C21.sub.0.002 C22.sub.0.717 T = +41.3.degree                                   . C. δ = 1.2                               C19.sub.0.001 C20.sub.0.184 C21.sub.0.003 C22.sub.0.812 T = +42.0.degree                                   . C. δ = 0.9                               C20.sub.0.09 C22.sub.0.90 C21.sub.0.01 T = +42.8° C. δ =                                      0.9                                              C19.sub.0.001 C20.sub.0.093 C21.sub.0.003 C22.sub.0.903 T = +42.9.degree                                   . C. δ = 1.0                             ______________________________________                                    

C21-C23: ε_(n) =0.90; T=7.1° C.

C21_(1-x) C23_(x)

0≦x≦0.35: δ=1

0.35<x<0.60: δ=2

0.60≦x≦1: δ=1

Doped formulations:

C21₀.580 C23₀.400 C22₀.020 : T=43.3° C., δ=1.2, H=152 J/g

Fourth Case : n≧22 ε_(n) >0.90 T<7° C.

From C22-C24 inclusive, all the binaries have total miscibilities withδ<1, whatever the value of x may be. The same thing applies to the dopedbinaries. The following are a few examples of doped binaries,compementary examples being given in Table 2.

C22-C24: ε_(n) =0.91; T=6.5° C.

C22₀.70 C24₀.28 C20₀.02 T=+45.2° C., δ=0.8, H=153 J/g

C22₀.68 C24₀.30 C26₀.02 T=+45.7° C., δ=0.8, H=153 J/g

C22₀.30 C24₀.68 C20₀.02 T=+48.1° C., δ=0.9, H=155 J/g

C22₀.28 C24₀.70 C23₀.02 T=+48.4° C., δ=0.9 H=156 J/g

C23-C25 : ε_(n) =0.91 ; T=6.1° C.

C23₀.100 C25₀.890 C24₀.010 :T=+53.0° C.,δ=0.9,H=161 J/g

C24-C26 : ε_(n) =0.92 ;T=5.5° C.

C24₀.90 C26₀.08 C20₀.02 : T=+50.2° C., δ=0.4, H=158 J/g

C24₀.49 C26₀.50 C20₀.01 : T=+52.2° C., δ=0.9, H=158 J/g

C24₀.49 C26₀.50 C22₀.01 : T=+53.5° C., δ=0.19,H=162 J/g

If n continues to increase, alloys can readily be obtained in which δ islower than 0.5 even for the central concentrations, whatever x may be.The following are two examples:

C30-C32: ε_(n) =0.93 ; T=3.9° C.

δ≦0.5 for every x of C30_(1-x) C32_(x)

Example: C30₀.50 C32₀.50 T=+67.0° C., δ=0.2, H=160 J/g

C44-C46: ε_(n) =0.95; T=1.6° C.

δ<0.5 for every x of C⁴⁴ _(1-x) C46_(x)

Example: C44₀.50 C46₀.50 T=+87.4° C.,δ=0.2,H=220 J/g

2) Non-consecutive ALCALs

First case: type Cnp C(np+4) and type Cni C(ni+4)

We find substantially the same evolution as for the consecutive ALCALswith an increase in the extent of the zones of miscibility and animprovement in the quality of the thermal window as n increases and Tdiminishes, the latter parameter being determining.

ε_(n) ≧0.80 is necessary to have miscibility in all proportions.Moreover, we must have T≦10° C. for all the alloys to have δ≦2. ε_(n)≧0.90 is necessary for all the alloys to have their δ≦1.

Examples of formulations

C18-C22 : ε_(n) =0.78 ;T=16.2° C.

C¹⁸.sub.(1-x) C²² _(x) acceptable for 0.05<x≦0.20 with δ=2

0.20<x≦0.40 with δ=4

0.90≦x≦1 with δ=4

C18₀.870 C22₀.100 C20₀.030 :T=+27.8 δ=1.8, H=164 J/g

C18₀.700 C22₀.280 C20₀.020 :T=+30.8 δ=3.9, H=139 J/g

C22-C26 : ε_(n) =0.82 ;T=12.0° C.

C22.sub.(1-x) C26_(x) acceptable for 0≦x≦0.35 with δ=2

0.35<x<0.75 with δ=4

0.75≦x≦1 with δ=2

C22₀.500 C26₀.490 C24₀.010 :T=+50.2° C., δ=2.6, H=157 J/g

C28-C32 : ε_(n) =0.86; T=8.3° C.

C28.sub.(1-x) C32_(x) acceptable for 0≦x≦0.30 with δ=1

0.30<x≦0.90 with δ=2

0.90<x≦1 with δ=1

C28₀.790 C32₀.200 C30₀.010 :T=+62.4° C., δ=0.4, HH =160 J/g

C46-C50 : ε_(n) =0.91; T=4.1° C.

δ<1 whatever the content may be

C46₀.100 C50₀.890 C44₀.010 :T=+91.9° C. δ=0.6, H=215 J/g

2nd case: type Cnp C(np+k) and type Cni C(ni+k) where k is an evennumber greater than 4.

To obtain fairly extensive ranges of miscibility with good δs, use ismade of relatively high nps (or nis), so as to have simultaneouslyε_(n) >0.80 and T <10° C.

Examples of binaries with k=6

C26-C32 : ε_(n) =0.77; T=13.3° C.

Total miscibility, but the loop is wide in the direction of C32. As aresult, we have:

C26.sub.(1-x) C32_(x) acceptable for 0≦x≦0.10 with δ=1

0.10<x≦0.25 with δ=2

0.25<x≦0.45 with δ=4

0.90≦x≦1 with δ=4

C26₀.800 C32₀.190 C30₀.010 :T=+57.3° C., δ=2.0, H=160 J/g

C44-C50: ε_(n) =0.86; T=5.7° C.

C44.sub.(1-x) C50_(x) acceptable for every x

for 0≦x≦0.32 with δ=1

0.32<x<0.75 with δ=2

0.75≦x≦1 with δ=1

C44₀.395 C50₀.585 C46₀.005 C48₀.015 :T=+89.2° C.,δ=1.5,H=225 J/g

If the nps or nis are low and/or if k is high, acceptable solutions willbe obtained in the form of eutectic mixtures of alloys (with δstherefore not differing much from 0° C.).

For example,

C23-C33 : ε_(n) =0.57 ;T=23.7° C.

Eutectic at T+46° C.

II Binary ALCALs with different parity

One of A and B belongs to the even alcanes, the other to the oddalcanes, or vice verse.

1) Consecutive ALCALs

They are of type Cnp/Cni with i=p+1 or Cni/Cnp with p=i+1.

As in the preceding cases, in fact a favourable effect is observed fromthe lengthening of the chain. Nevertheless, in this case considerationmust be given to the effect of non-isomorphism which characterizes thepairs Cnp/Cni or Cni/Cnp, as long as the ns are less than 21. Two casescan therefore be distinguished:

First case:

At lease one of the constituents has n<21. In this case miscibilitycould not be total, but as soon as the ε_(n) s are higher than 0.90, foreach binary, two relatively narrow partial loops are observced whichintersect one another in a zone excluded according to the invention fromthe point of view of δ, a zone systematically shifted in the directionof the even Cn.

Examples of binaries:

C12-C13: ε_(n) =0.92; T=4.1° C.

We have acceptable alloys C12.sub.(1-x) C13_(x) as soon as x≧0.30

0.30≦x<0.90 avec δ=4

0.90≦x≦1 avec δ=2

with more particularly:

the following undoped formulations:

C12₀.700 C13₀.300 : T=-13.6° C., δ=2.6,H=146 J/g

C12₀.500 C13₀.500 : T=-11.4° C., δ=2.2,H=146 J/g

the following doped formulations:

C12₀.690 C13₀.300 C11₀.010 : T=-13.5° C.,δ=2.7,H=146 J/g

C12₀.480 C13₀.480 C11₀.040 : T=-11.8° C.,δ=2.2,H=146 J/g

C12₀.200 C13₀.780 C11₀.020 : T=-8.0° C., δ=2.4,H=150 J/g

C13-C14: ε_(n) =0.92,T=11.4° C.

We have alloys C13.sub.(1-x) C14_(x) where x ≦0.50

0≦x<0.07 with δ=1

0.07≦x≦0.50 with δ=2

with more particularly

as undoped formulations:

C13₀.700 C14₀.300 : T=-3.8° C., δ=1.2, H=153 J/g

C13₀.500 C14₀.500 : T=-2.3° C., δ=1.7, H=152 J/g as doped formulations:

C13₀.690 C14₀.30 C15₀.010 :T=-3.9° C.δ=1.4,H=152 J/g

C13₀.485 C14₀.490 C15₀.025 :T=-2.5° C., δ=1.8,H=152 J/g

C14-C15 : ε_(n) =0.93,T=4.1° C.

We have alloys C14.sub.(1-x) C15_(x) when x>0.20

0.20<x<0.70 with δ=4

0.70≦x<0.90 with δ=2

0.90≦x≦1 with δ=1

Examples of doped formulations:

C14₀.400 C15₀.570 C13₀.030 :T=+5.2° C., δ=3.9, H=147 J/g

C14₀.260 C15₀.700 C6₀.040 : T=+7.7° C., δ=2.0, H=155 J/g

C15-C16 : ε_(n) =0.93,T=8.2° C.

We have alloys C15.sub.(1-x) C16_(x) except if 0.70<x<0.90

0≦x≦0.25 with δ=1

0.25<x≦0.70 with δ=2

0.90≦x≦1 with δ=4

Examples of doped formulations:

C15₀.840 C16₀.130 C14₀.030 :T=+9.5° C., δ=1.0,H=153 J/g

C15₀.840 C16₀.150 C14₀.010 :T=+10.5° C., δ=0.8 H=150 J/g

C15₀.690 C16₀.300 C14₀.010 :T=+11.2° C., δ=1.3H=156 J/g

C16-C17 : ε_(n) =0.94, T=3.8° C.

We have alloys C16.sub.(1-x) C17_(x) si x>0.10

0.10<x≦0.40 with δ=1

0.40<x≦0.90 with δ=2

0.90<x≦1 with δ=1

Examples of doped formulations:

C16₀.300 C17₀.685 C15₀.010 C18₀.005 :T=19.8° C., δ=1.5,H=160 J/g

C16₀.100 C17₀.885 C15₀.005 C18₀.010 :T=21.3° C.,δ=1.1,H=165 J/g

C17-C18 : ε_(n) =0.94 ;T=6.4° C.

We have alloys C17.sub.(1-x) C18_(x) for x<0.75

0≦x≦0.50 with δ=1

0.50<x<0.75 with δ=2

Example of doped formulation:

C17₀.300 C18₀.690 C19₀.010 :T=+25.7° C., δ=1.2, H=159 J/g

C19-C20 : ε_(n) =0.95; T=4.7° C.

We have alloys C19.sub.(1-x) C20_(x) avec δ<1 whatever may be, x exceptbetween 0.90<x<1

Example of doped formulation:

C19₀.300 C20₀.680 C21₀.020 : T=+35.2° C., δ=0.9, H=151 J/g

Second case:.All the constituents have n>21

Since the phases are isomorphic prior to melting of the even and oddalcanes, total miscibility is possible and actually occurs, moreparticularly since the ε_(n) s are higher than or equal to 0.95.

C21-C22 : ε_(n) =0.95;T=3.9° C.

All the alloys C21.sub.(1-x) C²² _(x) are acceptable with δ<1.

Example of doped formulation:

C21₀.490 C22₀.490 C23₀.020 :T=+41.84° C., δ=0.6, H=150 J/g

C22-C23 : ε_(n) =0.95;T=3.2° C.

All the alloys C²².sub.(1-x) C23_(x) are acceptable with δ<1.

Example of doped formulation:

C22₀.490 C23₀.500 C24₀.010 :T=+45.7° C., δ=0.5, H=155 J/g

C24-C25 : ε_(n) =0.96;T=2.8° C.

Example of doped formulation:

C24₀.500 C25₀.490 C26₀.010 :T=+51.7° C., δ=0.4,H=159 J/g

C35-C36 : ε_(n) =0.97;T=1.1° C.

Example of doped formulation:

C35₀.890 C36₀.090 C37₀.020 :T=+75.2° C., δ=0.4, H=160 J/g

2) Non-consecutive ALCALs

If wide ranges of acceptable concentrations are desired, components withε_(n) higher than 0.90 should be selected, or eutectic mixtures ofalloys with low ε_(n) s can be used.

Example:

C15-C22: ε_(n) =0.53;T=34.4° C.

Eutectic at T +9° C.

Example 5: ALCAL ternaries:

a) Study of evolutionn.

The ternaries will be presented in the following manner; Cn1--Cn2--Cn3with n1<n2<n3, also corresponding to the increased order of the meltingtemperature.

For each ternary the ε_(n) s will be given for the components taken inpairs in the following order: Cn1-Cn2; Cn2-Cn3 and Cn1-Cn3. This thirdvalue will always be the lowest, having regard to the system adopted.

1) Ternary with all consecutive Cns: These are ternariesCn-C(n+1)-C(n+2)

The following will be mentioned by way of example:

    ______________________________________                                        Cn1  Cn2  Cn3                                                                             ε.sub.1.2                                                                         ε.sub.2.3                                                                    ε.sub.1.3                              ______________________________________                                        C14-C15-C16 0.93        0.93   0.86                                             C15-C16-C17 0.93 0.94 0.87                                                    C20-C21-C22 0.95 0.95 0.90                                                    C22-C23-C24 0.95 0.96 0.91                                                  ______________________________________                                    

The extent of the acceptable ranges of concentrations increases as thedifferent ε₁.2 ; ε₂.3 et ε₁.3 increase. For the system C14--C15--C16 andC15--C16--C17 where ε₁.3 <0.90, the quality ranges δ=1 and δ=2 are notvery extensive, and levels exist where δ>4. If all the ε_(n) ≧0.90, allthe formulations have at least the attributes δ≦2 (case ofC20--C21--C22, except for a small zone disturbed by the solid-solidtransition of C20) and even the attribute δ≦1 (case of C22--C23--C24).

2) Ternaries with not directly consecutive Cns

First general case: ternaries Cn-C(n+2)-C(n+4). There are, for example,the following ternaries (3 cases of which are given in detailhereinafter).

    ______________________________________                                        Cn1  Cn2  Cn3                                                                             ε.sub.1.2                                                                         ε.sub.2.3                                                                    ε.sub.1.3                              ______________________________________                                        C18-C20-C22 0.89        0.90   0.78                                             C20-C22-C24 0.90 0.91 0.80                                                    C21-C23-C25 0.90 0.91 0.81                                                    C22-C24-C26 0.91 0.92 0.82                                                  ______________________________________                                    

The same phenomenon is found as previously: increase in the extent ofthe levels with the better attribute with an increase in the three ε_(n)concerned, ε₁.3 being the most decisive, since it brings into play thetwo Cns furthest away in the length of the chain.

Second general case

In proportion as the distances between the various Cns concerned aregreater, the greater the increase must be in the scale of the alcanes,classified by their n, to obtain important levels of ALCALs having asatisfactory δ. The following are two complete examples:

C20-C22-C26 0.90 0.82 0.70

C44-C46-C50 0.95 0.91 0.86

If for the first one there are wide ranges of formulations with theattribute δ>6, in contrast for the second one, the majority of theformulations have a attribute δ≦1 and the others have a 1<δ≦2.

With a reduction in the case of the ns and/or if the distance betweenthe Cns is increased, eutectic mixtures of alloys can moreover begenerated.

b): Examples

1. Study of the ternary ALCALs xC14-yC15-zC16

FIG. 1 is a diagram giving the attributes of the different alloys. Thediagram shows eight zones (surfaces numbered S₁ to S₈).

One zone where δ≦1: S₁

Definition of the zone S₁ ##EQU4## with more particularly the followingexamples:

    ______________________________________                                        x = 0.03 y = 0.84     z = 0.13                                                                              T.sub.δ  = +9.5.sub.1.0                     x = 0.01 y = 0.84 z = 0.15 T.sub.δ  = +10.5.sub.0.8                   ______________________________________                                    

Two zones where 1<δ≦2: S₂ and S₃

Definition of the zone S₂ =S not including S₁ where S ##EQU5## with moreparticularly the following examples:

    ______________________________________                                        x = 0.01 y = 0.49     z = 0.50                                                                              T.sub.δ  = +12.3.sub.1.7                    x = 0.01 y = 0.69 z = 0.30 T.sub.δ  = +11.2.sub.1.3                     x = 0.07 y = 0.56 z = 0.37 T.sub.δ  = +10.7.sub.2.0                     x = 0.26 y = 0.67 z = 0.07 T.sub.δ  = +7.7.sub.2.0                    ______________________________________                                    

Definition of the zone S₃ ##EQU6## with more particularly the followingexamples:

    ______________________________________                                        x = 0.73 y = 0.14     z = 0.13                                                                              T.sub.δ  = +3.6.sub.2.0                     x = 0.89 y = 0.01 z = 0.10 T.sub.δ  = +3.2.sub.1.9                      x = 0.79 y = 0.01 z = 0.20 T.sub.δ  = +2.9.sub.2.0                    ______________________________________                                    

Two zones where 2<δ≧4: S4 and S₅

Definition of S₄ ##EQU7## with more particularly the following example:

    ______________________________________                                        x = 0.10 y = 0.01     z = 0.89                                                                              T.sub.δ  = +16.0.sub.3.2                  ______________________________________                                    

Definition of S₅

total triangle excluding: S₁ S₂ S₃ S₄ S₆ S₇ and S8 with moreparticularly the following examples:

    ______________________________________                                        x = 0.14 y = 0.23     z = 0.63                                                                              Tδ = +11.9.sub.3.1                          x = 0.21 y = 0.56 z = 0.23 T.sub.δ  = +8.5.sub.2.3                      x = 0.24 y = 0.33 z = 0.43 T.sub.δ  = +9.5.sub.3.9                      x = 0.43 y = 0.33 z = 0.24 T.sub.δ  = +6.5.sub.2.6                      x = 0.57 y = 0.17 z = 0.26 T.sub.δ  = +5.3.sub.2.6                      x = 0.64 y = 0.01 z = 0.35 T.sub.δ  = +4.7.sub.2.8                    ______________________________________                                    

Two zones where 4<δ≦6: S₆ et S₇

Definition of S₆ ##EQU8## with more particularly the following examples:

    ______________________________________                                        x = 0.33 y = 0.07     z = 0.60                                                                              T.sub.δ = +9.9.sub.4.4                      x = 0.41 y = 0.01 z = 0.58 T.sub.δ = +8.8.sub.4.9                       x = 0.32 y = 0.24 z = 0.44 T.sub.δ = +8.8.sub.4.4                     ______________________________________                                    

Definition of S₇ ##EQU9##

One zone where δ>6 : S₈

Definition of S₈ ##EQU10## with more particularly the following example:

    ______________________________________                                        x = 0.17 y = 0.07     z = 0.76                                                                              T.sub.δ  = +13.8.sub.7.4                  ______________________________________                                    

2. Study of the ternary ALCALs xCi5-yC16-zC17

FIG. 2 is a diagram giving the attributes of the different alloys.

Five zones are distinguished (surfaces numbered from S₁ to S₅).

A zone where δ≦1: S₁

Definition of S₁ ##EQU11## with more particularly the followingexamples:

    ______________________________________                                        x = 0.83 y = 0.15     z = 0.02                                                                              T.sub.δ  = +10.6.sub.0.8                    x = 0.87 y = 0.07 z = 0.06 Tδ = 10.3.sub.1.0                          ______________________________________                                    

A zone where 1<δ≦2: S₂

Definition of S₂

total triangle excluding S₁ S₃ S₄ S₅ with more particularly thefollowing examples:

    ______________________________________                                        x = 0.77 y = 0.17     z = 0.06                                                                              T.sub.δ  = +10.8.sub.1.3                    x = 0.77 y = 0.07 z = 0.16 T.sub.δ  = +10.9.sub.1.4                     x = 0.67 y = 0.30 z = 0.03 T.sub.δ  = +11.4.sub.1.4                     x = 0.50 y = 0.48 z = 0.02 T.sub.δ  = +12.4.sub.1.7                     x = 0.36 y = 0.47 z = 0.17 T.sub.δ  = +13.5.sub.2.0                     x = 0.27 y = 0.66 z = 0.07 T.sub.δ  = +14.9.sub.2.0                     x = 0.70 y = 0.03 z = 0.27 T.sub.δ  = +11.4.sub.1.4                     x = 0.06 y = 0.67 z = 0.27 T.sub.δ  = +16.5.sub.1.9                     x = 0.03 y = 0.27 z = 0.70 T.sub.δ  = +19.5.sub.1.6                   ______________________________________                                    

One zone where 2<δ≦4: S₃

Definition of the zone S₃ : S not including S₅ ##EQU12## with moreparticularly the following examples:

    ______________________________________                                        x = 0.44 y = 0.23     z = 0.33                                                                              T.sub.δ  = +14.1.sub.2.6                    x = 0.27 y = 0.47 z = 0.26 T.sub.δ  = +14.8.sub.2.3                     x = 0.27 y = 0.07 z = 0.66 T.sub.δ  = +17.1.sub.3.9                     x = 0.06 y = 0.07 z = 9.87 T.sub.δ  = +20.4.sub.2.5                   ______________________________________                                    

Two zones where δ<4: S₄ and S₅

Definition of S₄ ##EQU13## with more particularly the following example:

    ______________________________________                                        x = 0.40 y = 0.02     z = 0.58                                                                              T.sub.δ  = +15.8.sub.4.3                  ______________________________________                                    

Definition of S₅ ##EQU14## with more particularly the following example:

    ______________________________________                                        x = 0.10 y = 0.88     z = 0.02                                                                              T.sub.δ  = +17.0.sub.4.2                  ______________________________________                                    

3: Study of the ternary ALCALs xC20-yC21-zC22

FIG. 3 is a diagram showing the attributes of the different alloys.Three zones can be distinguished (surfaces numbered from S₁ to S₃)

One zone where δ≧1: S₁

Definition of the zone S₁ total triangle excluding S₂ and S₃ with moreparticularly the following examples:

    ______________________________________                                        x = 0.09 y = 0.01     z = 0.90                                                                              T.sub.δ  = +42.8.sub.0.9                    x = 0.50 y = 0.47 z = 0.03 T.sub.δ  = +38.2.sub.0.6                     x = 0.80 y = 0.03 z = 0.17 T.sub.δ  = + 37.5.sub.0.8                    x = 0.03 y = 0.47 z = 0.50 T.sub.δ  = +41.6.sub.0.6                   ______________________________________                                    

A zone where 1<δ≦2: S₂

Definition of the zone S₂ ##EQU15##

    ______________________________________                                        x = 0.30 y = 0.01     z = 0.69                                                                              T.sub.δ  = +41.2.sub.1.4                    x = 0.48 y = 0.03 z = 0.49 T.sub.δ  = +39.7.sub.1.5                     x = 0.33 y = 0.34 z = 0.33 T.sub.δ  = +39.5.sub.1.3                   ______________________________________                                    

A zone where δ<4: S₃

Definition of the zone S₃ ##EQU16##

4: Study of the ternary ALCALs xC22-yC23-zC24

The diagram of the attributes of the different alloys shown in FIG. 4 ischaracterized by the existence of a single zone called S where δ≧1

Definition of the zone S:

the whole ternary, that is x+y+z=1 with more particularly the followingexamples:

    ______________________________________                                        x = 0.05 y = 0.02     z = 0.93                                                                              T.sub.δ  = +50.2.sub.0.4                    x = 0.28 y = 0.02 z = 0.70 T.sub.δ  = +48.4.sub.0.9                     x = 0.33 y = 0.34 z = 0.33 T.sub.δ  = +47.1.sub.0.7                     x = 0.70 y = 0.02 z = 0.28 T.sub.δ  = +45.7.sub.0.9                     x = 0.48 y = 0.50 z = 0.02 T.sub.δ  = +45.8.sub.0.6                     x = 0.03 y = 0.47 z = 0.50 T.sub.δ  = +48.9.sub.0.5                   ______________________________________                                    

5: Study of the ternary ALCALs xCl8-yC20-zC22

FIG. 5 is a diagram showing the attributes of the different alloys.Seven zones can be distinguished (surfaces numbered from S₁ to S₇).

One zone where δ≦1: S₁

Definition of the zone S₁ : S not including S₇ ##EQU17## with moreparticularly the following examples:

    ______________________________________                                        x = 0.06 y = 0.88     z = 0.06                                                                              T.sub.δ  = +36.1.sub.1.0                    x = 0.03 y = 0.77 z = 0.20 T.sub.δ  = 37.5.sub.0.9                    ______________________________________                                    

One zone where 1<δ≦2: S₂

Definition of the zone S₂ :

total triangle excluding S₁, S₃, S₄, S₅, S₆ and S₇ with moreparticularly the following examples:

    ______________________________________                                        x = 0.78 y = 0.20     z = 0.02                                                                              T.sub.δ  = +28.5.sub.2.0                    x = 0.53 y = 0.44 z = 0.03 T.sub.δ  = +30.9.sub.2.0                     x = 0.19 y = 0.80 z = 0.01 T.sub.δ  = +33.9.sub.2.0                     x = 0.63 y = 0.24 z = 0.13 T.sub.δ  = +30.0.sub.1.9                     x = 0.06 y = 0.56 z = 0.38 T.sub.δ  = +37.8.sub.1.3                     x = 0.40 y = 0.58 z = 0.02 T.sub.δ  = +40.1.sub.1.5                     x = 0.18 y = 0.80 z = 0.02 T.sub.δ  = +41.8.sub.1.1                     x = 0.87 y = 0.10 z = 0.03 T.sub.δ  = +27.8.sub.1.8                   ______________________________________                                    

One zone where 2<δ≦4: S₃

Definition of the zone S₃ : S excluding S₄ and S₅ ##EQU18## with moreparticularly the following examples:

    ______________________________________                                        x = 0.23 y = 0.54     z = 0.23                                                                              T.sub.δ  = 35.3.sub.2.7                     x = 0.33 y = 0.34 z = 0.33 T.sub.δ  = +35.7.sub.3.7                     x = 0.13 y = 0.33 z = 0.54 T.sub.δ  = +38.6.sub.2.6                     x = 0.70 y = 0.28 z = 0.02 T.sub.δ  = +30.8.sub.3.9                   ______________________________________                                    

One zone where 4<δ≦6: S₄

Definition of the zone S₄ ##EQU19## with more particularly the followingexample:

    ______________________________________                                        x = 0.43 y = 0.14     z = 0.43                                                                              T.sub.δ  = +35.8.sub.5.1                  ______________________________________                                    

Three zones where δ<6: S₅, S₆ and S₇

Definition of S₅ : ##EQU20## with more particularly the followingexamples:

    ______________________________________                                        x = 0.48 y = 0.02     z = 0.50                                                                              T.sub.δ  = +36.3.sub.6.5                    x = 0.27 y = 0.06 z = 0.67 T.sub.δ  = +39.2.sub.7.4                   ______________________________________                                    

Definition of S₆ ##EQU21##

Definition S₇ ##EQU22##

6: Study of the ternary ALCALs xC20-yC22-zC24

In the diagram showing the attributes of the different alloys (FIG. 6),five zones can be distinguished (surfaces numbered from S₁ to S₅).

Two zones where δ≦1: S₁ and S₂

Definition of S₁ : ##EQU23## with more particularly the followingexamples:

    ______________________________________                                        x = 0.02 y = 0.30     z = 0.68                                                                              T.sub.δ  = +48.1.sub.0.9                    x = 0.02 y = 0.70 z = 0.28 T.sub.δ  = +45.2.sub.0.8                     x = 0.07 y = 0.76 z = 0.17 T.sub.δ  = +44.7.sub.0.9                   ______________________________________                                    

Definition of S₂ : ##EQU24## with more particularly the followingexamples:

    ______________________________________                                        x = 0.78 y = 0.20     z = 0.02                                                                              T.sub.δ  = +38.0.sub.0.8                  ______________________________________                                    

A zone where 1≦δ<2: S₃

Definition of S₃

total triangle excluding S₁, S₂, S₄ and S₅ with more particularly thefollowing examples:

    ______________________________________                                        x = 0.05 y = 0.02     z = 0.93                                                                              T.sub.δ  = +50.5.sub.1.1                    x = 0.17 y = 0.66 z = 0.17 T.sub.δ  = +43.3.sub.1.2                     x = 0.37 y = 0.46 z = 0.17 T.sub.δ  = +42.0.sub.1.9                     x = 0.38 y = 0.60 z = 0.02 T.sub.δ  = +40.6.sub.1.4                     x = 0.50 y = 0.48 z = 0.02 T.sub.δ  = +40.0.sub.1.5                     x = 0.66 y = 0.17 z = 0.17 T.sub.δ  = +39.0.sub.1.6                     x = 0.87 y = 0.02 z = 0.11 T.sub.δ  = +38.6.sub.1.2                   ______________________________________                                    

A zone where 2<δ≦4: S₄

Definition of S₄ : ##EQU25## with more particularly the followingexamples:

    ______________________________________                                        x = 0.23 y = 0.03     z = 0.74                                                                              T.sub.δ  = +47.0.sub.3.0                    x = 0.17 y = 0.37 z = 0.46 T.sub.δ  = +45.6.sub.2.2                     x = 0.47 y = 0.06 z = 0.47 T.sub.δ  = +43.4.sub.3.7                     x = 0.34 y = 0.33 z = 0.33 T.sub.δ  = +43.4.sub.2.8                     x = 0.40 y = 0.20 z = 0.40 T.sub.δ  = +43.3.sub.3.3                     x = 0.66 y = 0.07 z = 0.27 T.sub.δ  = +39.9.sub.2.3                   ______________________________________                                    

A zone where δ<4: S₅

Definition of S₅ ##EQU26##

7: Study of the ternary ALCALs xC22-YC24-zC26

FIG. 7 is a diagram showing the attributes of the different alloys.Three zones can be distinguished (surfaces numbered from S₁ to S₃)

One zone where δ≦1: S₁

Definition of S₁ : ##EQU27## with more particularly the followingexamples:

    ______________________________________                                        x = 0.01 y = 0.49     z = 0.50                                                                              T.sub.δ  = +53.5.sub.0.9                    x = 0.03 y = 0.95 z = 0.02 T.sub.δ  = +50.5.sub.0.5                     x = 0.17 y = 0.66 z = 0.17 T.sub.δ  = +50.3.sub.0.8                     x = 0.30 y = 0.68 z = 0.02 T.sub.δ  = +48.6.sub.0.9                     x = 0.46 y = 0.37 z = 0.17 T.sub.δ  = +47.7.sub.1.1                     x = 0.68 y = 0.30 z = 0.02 T.sub.δ  = +45.7.sub.0.8                   ______________________________________                                    

One zone where 1<δ≦2:S₂

Definition of the zone S₂ : total triangle excluding SI and S₃ with moreparticularly the flowing examples:

    ______________________________________                                        x = 0.10 y = 0.18     z = 0.72                                                                              T.sub.δ  = +54.0.sub.1.9                    x = 0.66 y = 0.07 z = 0.27 T.sub.δ  = +47.2.sub.1.6                     x = 0.34 y = 0.33 z = 0.33 T.sub.δ  = +44.3.sub.1.4                   ______________________________________                                    

One zone where 2<δ≦4: S₃

Definition of S₃ ##EQU28## with more particularly the followingexamples:

    ______________________________________                                        x = 0.27 y = 0.07     z = 0.66                                                                              T.sub.δ  = +52.2.sub.2.4                    x = 0.50 y = 0.01 z = 0.49 T.sub.δ  = +50.2.sub.2.6                     x = 0.40 y = 0.20 z = 0.40 T.sub.δ  = +49.7.sub.2.1                     x = 0.47 y = 0.06 z = 0.47 T.sub.δ  = +49.8.sub.2.4                   ______________________________________                                    

8: Study of the ternary ALCALs xC20-yC22-zC26

FIG. 8 is a diagram showing the attributes of the different alloys.Seven zones can be distinguished (surfaces numbered S₁ to S₇).

Two zones where δ≦1: S₁ and S₂

Definition of the zone S₁ ##EQU29## with more particularly the followingexamples:

    ______________________________________                                        x = 0.20 y = 0.78     z = 0.02                                                                              T.sub.δ  = +42.2.sub.0.9                    x = 0.07 y = 0.90 z = 0.03 T.sub.δ  = +43.3.sub.1.0                   ______________________________________                                    

Definition of the zone S₂ ##EQU30## with more particularly the followingexamples:

    ______________________________________                                        x = 0.78 y = 0.20     z = 0.02                                                                              T.sub.δ  = +37.8.sub.0.8                    x = 0.67 y = 0.30 z = 0.03 T.sub.δ  = +38.6.sub.0.9                   ______________________________________                                    

Two zones where 1<δ≦2: S₃ and S₄

Definition of S₃ ##EQU31##

Definition of S₄ : S excluding S₁,S₂ and S₇ ##EQU32## with moreparticularly the following examples:

    ______________________________________                                        x = 0.63 y = 0.23     z = 0.14                                                                              T.sub.δ  = +39.5.sub.1.8                    x = 0.58 y = 0.40 z = 0.02 T.sub.δ  = +39.1.sub.1.1                     x = 0.47 y = 0.50 z = 0.03 T.sub.δ  = +40.4.sub.1.5                     x = 0.30 y = 0.67 z = 0.03 T.sub.δ  = +41.8.sub.1.4                     x = 0.13 y = 0.74 z = 0.13 T.sub.δ  = +43.8.sub.1.5                   ______________________________________                                    

One zone where 2<δ≦4: S₅ =S not including S₆

Definition of S₅ : S excluding S₆ ##EQU33## with more particularly thefollowing examples:

    ______________________________________                                        x = 0.03 y = 0.47     z = 0.50                                                                              T.sub.δ  = +50.0.sub.3.5                    x = 0.37 y = 0.46 z = 0.17 T.sub.δ  = +42.6.sub.2.6                     x = 0.77 y = 0.03 z = 0.20 T.sub.δ  = +38.8.sub.2.1                     x = 0.10 y = 0.02 z = 0.88 T.sub.δ  = +54.5.sub.3.7                   ______________________________________                                    

Two zones where δ≦6: S₆ and S₇

Definition of S₆ ##EQU34## with more particularly the following example:

    ______________________________________                                        x = 0.33 y = 0.34     z = 0.33                                                                              T.sub.δ  = +46.6.sub.6.0                  ______________________________________                                    

Definition of S₇ ##EQU35##

9: Study of the ternary ALCALs xC44-yC46-zC50

In the diagram showing the-attributes of the different alloys (FIG. 9)two zones can be distingushed (surfaces numbered from S₁ to S₂).

One zone where δ≦1: S₁

Definition of S₁

Total triangle not including S₂ with more particularly the followingexamples:

    ______________________________________                                        x = 0.78 y = 0.02     z = 0.20                                                                              T.sub.δ  = +86.7.sub.0.7                    x = 0.40 y = 0.40 z = 0.20 T.sub.δ  = +87.2.sub.0.5                   ______________________________________                                    

One zone where 1<δ≦2 : S₂

Definition of S₂ ##EQU36## with more particularly the following example:

    ______________________________________                                        x = 0.40 y = 0.02     z = 0.58                                                                              T.sub.δ  = +89.2.sub.1.5                  ______________________________________                                    

Example 6: Quaternary and higher ALCALs

The same considerations concerning the various ε_(n) s of theconstituents taken in pairs enable multi-component ALCALs to be producedwhich are acceptable as regards their attribute δ.

Examples of formulations:

C14₀.330 C15₀.390 C16₀.140 C18₀.140 :T=+7.5° C. δ=3.4.H=127 J/g

C14₀.290 C15₀.350 C16₀.130 C17₀.230 :T=+8.6° C. δ=4.0.H=146 J/g

C44₀.350 C46₀.350 C48₀.100 C50₀.200 :T=+86.9° C. δ=0.6,H=220J/g

C44₀.300 C15₀.360 C16₀.140 C17₀.06 C18₀.140 : T=+7.6° C., δ=3.5, H=128J/g

Example 7: Molecular alloys formed by monoacid-monoacid chains: thefollowing results were obtained with the formulation:

[CH₃ (CH₂)₁₈ COOH]₀.52 [CH₃ (CH₂)₂₀ COOH]₀.48 : T=+69.° C., δ=0.9, H=204J/g

Example 8: Molecular alloys formed by alcane-diacid chains: with thefollowing formulation:

[C₂₂ H₄₆ ]₀.80 [COOH (CH₂)₂₀ COOH]₀.20, we obtain:

T=+44.3° C., δ=1.7 ,H=188 J/g

Example 9: Molecular alloys formed by monoacid-diacid chains.

An advantageous eutectic mixture of alloys corresponds to the followingglobal composition:

0.94 of [CH₃ (CH₂)₂₀ COOH] with

0.06 of [COOH (CH₂)₂₀ COOH]

T=+77.2° C., δ=0, H=160 J/g

Example 10: Application to the production of trays for market fish stalldisplays:

A display of trays containing ALCALs with attribute δ≦4. was covered. Incomparison with the ice at present used, the trays had the advantagethat they could be regenerated by cooling. If necessary they could beused under a small thickness of ice, which will be better preserved ifthe traditional presentation is desired.

Example 11: Application to the cold preservation of a transportedfoodstuff:

Let us suppose that a solid or liquid foodstuff which is to be preservedin its packaging in a conventional refrigerator is to be transported toa given place (for example, a work site or picnic area), for consumptionseveral hours later without any other means of protection and withoutits temperature exceeding 13° C. (for example). Advantageously, one ofthe ALCALs appearing in the following list of formulations will beselected. The selection is wide open; it will be made in dependence onthe parameters to be given precedence, more partiularly on economicconstraints and the availability of the base products:

    ______________________________________                                                          T (°C.)                                                                      δ (°C.)                                                                   HJ.g.sup.-1                                  ______________________________________                                        C14.sub.0.214 C15.sub.0.561 C16.sub.0.225                                                         +8.5    2.3      152                                        C14.sub.0.290 C15.sub.0.350 C16.sub.0.130 C17.sub.0.220 C18.sub.0.010                                            +8.6 4.1 146                               C14.sub.0.320 C15.sub.0.240 C16.sub.0.440 +8.6 4.4 151                        C14.sub.0.400 C16.sub.0.600 +9.0 4.9 148                                      C14.sub.0.107 C15.sub.0.592 C16.sub.0.220 C17.sub.0.059 C18.sub.0.022                                            +9.4 2.3 145                               C14.sub.0.030 C15.sub.0.840 C16.sub.0.130 +9.5 1.0 153                        C14.sub.0.240 C15.sub.0.330 C16.sub.0.430 +9.5 3.9 151                        C14.sub.0.330 C15.sub.0.070 C16.sub.0.600 +9.9 4.4 151                        C15.sub.0.870 C16.sub.0.070 C17.sub.0.060 +10.3 1.0 158                       C14.sub.0.010 C15.sub.0.840 C16.sub.0.150 +10.5 0.8 150                       C14.sub.0.030 C15.sub.0.640 C16.sub.0.330 +10.7 2.0 152                       C14.sub.0.066 C15.sub.0.505 C16.sub.0.369 +10.7 2.1 158                       C15.sub.0.770 C16.sub.0.170 C17.sub.0.060 +10.8 1.3 157                       C15.sub.0.770 C16.sub.0.070 C17.sub.0.160 +10.9 1.4 154                       C15.sub.0.700 C16.sub.0.300 +11.2 1.3 156                                     C15.sub.0.660 C16.sub.0.250 C17.sub.0.070 C18.sub.0.030 +11.2 1.9 152                                             C15.sub.0.700 C17.sub.0.300 +11.3                                            1.3 146                                    C15.sub.0.685 C17.sub.0.300 C16.sub.0.015 +11.3 1.3 146                       C15.sub.0.670 C16.sub.0.300 C17.sub.0.030 +11.4 1.4 155                       C14.sub.0.140 C15.sub.0.230 C16.sub.0.630 +11.9 3.1 147                     ______________________________________                                    

By way of example, if the first alloy in this list is chosen, a PCMMAwill be available which can be stored with 95% efficiency between +6.2°C. and +8.5° C.. Clearly, a man skilled in the art can readily deviseother suitable formulations.

It is sufficient to produce a double-walled packaging (completelyenclosing the foodstuff), between which the ALCAL will be placed; thethickness of ALCAL to be used will depend on the required protectionperiod. When the whole is placed in the refrigerator, the ALCAL willsolidify (since the temperature therein is lower than its T_(sol)) andthe whole will take on the temperature of the place in the refrigeratorwhere it is positioned. During transport of the whole at ambienttemperature, the ALCAL will form a barrier against the access of heat tothe actual foodstuff, since the heat coming from outside will first beabsorbed by the ALCAL to raise its temperature to T_(sol). Then all theheat will be taken by the ALCAL for its melting, and it is the H.menergy which will thus be blocked by the PCMMA (if m is its mass). Thetemperature of the whole will rise above T_(liq) only when all the ALCALhas melted.

Example 12: Application to cooling packings and heating covers.

A layer of ALCAL is incorporated on the packing or the cover. In theformer case the ALCAL is so selected that its operating temperature isof the order of +35° C. A stay in a cool room is enough to give thesystem its properties--i.e., to make the ALCAL solid. The patient willtherefore remain in contact with the surface at +35° C. as long as theheat which it gives off is not enough to make all the PCMMA melt.

In the second case the use of a heating resistance can be envisaged forthe storage of energy--i.e., to make an ALCAL melt which operates at+38° C., for example, with δ≦2; use is then possible without the usualrisks of heating covers, since the power is disconnected. Maintenancebetween +38° C. and +(38-δ)° C. will persist until the PCMMA hascompleted its transition.

Example 13: Heating mattress for operating tables and treatment tables.

Certain long lasting operations require assistance to the patient in theform of heat provided to compensate for hypothermia. The operatingprincipal of the heating cover (ALCAL with T=+38° C. and δ≦2, withincorporated resistance) can be adopted by associating therewith a lowvoltage system (for example, a battery) associated with a cycliccontactor to maintain the ALCAL in solid-liquid equilibrium during along lasting operation or during the transport of a patient. In thisexample, PCMMAs can be associated with other materials, such as fibrousor expanded materials, far reasons of comfort. Heat insulating layers onthe external surfaces (not in contact with the patient) will prolongautonomy of operation.

Example 14: Fondue.

A system is produced which has an incorporated resistance and operateswith power disconnected with a PCMMA (at a T higher than +100° C. andwith a δ≦4) placed in a double wall. The resulting apparatus thusensures high safety in its operation. The PCMMAs can advantageously beselected from the long-chain diacids.

Example 15: Cyclist's flask.

A double-walled flask was produced containing an ALCAL with δ≦4° C.operating at a temperature of the order of +15° C. (or even lower, asrequired); the cyclist will therefore have a refreshing drink forseveral hours, this being a great advantage in comparison withconventional flasks.

Example 16: Case for vaccines.

A double-walled case is prepared into which a PCMMA is introduced oftemperature T lower than approximately 15° C. with δ≦4. The PCMMA issolidified by placing it in a refrigerator. The case can be used fortransporting a vaccine.

This application is very advantageous, for example, to ramblers whohave, for example, an anti-viper vaccine, so that they can make theirtrip with improved safety.

The invention will therefore provide the means for producing PCMscorresponding to a wide range of temperatures required for industrialapplications.

In relation to the temperature level at which the phase change must takeplace, a man skilled in the art is provided with the means of selectingthe content of the organic compounds used to produce the alloy inconformity with the requirements defined hereinbefore.

What is claimed is:
 1. A phase change material comprising a compositionfor storing and restoring thermal energy by latent heat, consistingessentially of a single phase of a molecular alloy, consistingessentially of at least one compound represented by the formula (I)whereinA and Z are different, and each represents a saturated orunsaturated, optionally substituted acrylic organic compound having from2 to 120 carbon atoms, having the latent heat exhibited by aphase-change material, having a degree of molecular homeomorphism ₆₈ kgreater than 0.8, wherein when more than one compound of the formula (I)is present at least a pair of compounds exhibits a combined degree ofmolecular homeomorphism .sub.εk greater than 0.8, and wherein theinter-molecular interactions between A and Z are relatively comparable,x_(a) and x_(z) denote the molar proportions of A and Zrespectively,wherein said composition has the capacity of storing orrestoring thermal energy at a temperature T over a temperature range δnot exceeding 8° C. belongs to a phase diagram having, if the alloy isbinary, a loop in the case of total miscibility, or a partial loop inthe case of partial miscibility, or, if the alloy is ternary or above, atransition zone, said loop or zone lying in a temperature band includingthat which is required for a given application and whose geometric locusEGC (equal to the G curve) is slightly curved and close to horizontal,to ensure a δ not exceeding the required width, and a behaviorsatisfactory for thermal cycling; in the form of a packaging.
 2. Amethod of thermal protection and/or transport of agricultural feedstuffsat temperatures between -50° C. to +100° C. comprising enclosing saidfeedstuffs in a phase change material according to claim
 1. 3. A methodaccording to claim 2, for the transport or preservation of frozenproducts wherein the temperature is from 50° C. to -10° C.
 4. Methodaccording to claim 2, wherein the temperature is from -10° C. to +6° C.5. Method according to claim 2, wherein the temperature is higher than+16° C.
 6. Method according to claim 2, wherein the temperature ishigher than +16° C.
 7. Method according to claim 5, wherein thetemperature is between +35° C. to +100 ° C.
 8. Method according to claim1, wherein the phase change materials used are molecular alloys formedby alkanes.
 9. Method for packaging, isothermal or controlledtemperature handling, functional deficiencies and symptomatic therapiesin the paramedical field, using the materials according to claim
 1. 10.Method of protection for safety or energy saving over a temperaturerange from -80° C. to +200° C., using the materials according to claim1.